I certainly can take quite some time at times. At my home airport the fuel is extortionate, so most people who are based there have to factor in doing a short hop over to Chino to get the cheaper fuel. Add to this waiting for the IFR clearance once refueled, the drive there (45min) and it can take closer to 2 hrs at times. Obviously this can be mitigated by refueling the day before a long trip etc and if ATC is busy departing VFR and picking it up later. But most of my early IFR clearances have had no wait from ATC.
For a local flight I work on about 30 mins, and 15 mins to taxi. Covers off, pre flight etc. I like to do a post flight check when I return and I’m the only person that flies the plane so it’s usually fairly straight forward.
If it’s a longer trip where I need to take care of other things I usually allow longer, or if I want to be away early sort most things out the night before (10min drive to airfield).
The dream is to have the hangar / strip at home, then things become way easier again.
Slightly over 30 minutes…
Answering the question, if you own the plane and are the only one who flies it, things generally go a little faster. Nobody has access to my hangar or plane except me so that eliminates a lot of potential issues.
I park my car adjacent to the hangar, or inside the hangar if I’m going away. Fueling is often done at some convenient earlier time, like at the end of the previous flight. Getting either of my planes out of the hangar is a pain because they interfere with each other. I have a procedure, but it takes a few minutes.
After the plane is outside, I’m well known for taking a long time to get ready before I get into the plane. “Mission to Mars” is the phrase I’ve heard used, not sure what they mean 
Once I’m in the plane things typically go quicker, about 5 minutes to takeoff including startup, checking ATIS, taxi, run up and any waiting for traffic. That’s assuming I don’t strap in and then realize I’ve forgotten something and it’s locked in the hangar!
I mostly use my aircraft instead of a car, and usually allow 10-15 minutes from house to airborne, unless I’m in a rush. I think that’s typical for people who keep an aircraft at home – or vice versa.
Walk from house to shed is about 400 yards, so about 5 mins, which is a nice time to breathe some fresh air and engage brain.
The hangar is on my usual dog-walking circuit so we usually pre-flight and load fuel and/or cargo together the night before. Otherwise, fuel and pre-flight takes up to 5 mins, and at most another 5 mins to taxi out of the shed, belt up, set avionics, do various other pre-flight checks, line up about 15 degrees off the runway axis and ease the black knob forward.
Then it takes another six seconds to lift the wheels, which is the part I do quite like to rush. 
It usually takes no more than 20 minutes – 15 minutes is more normal (I can park right by the plane, no ATC or even radio operator) if I don’t need fuel. If I need fuel, I have to fly to Ronaldsway.
On the other hand time spent pottering around the aircraft preparing for flight is fun, so even if it takes longer because I have to drag the plane out the hangar with the tractor, that’s fine.
However, time spent in queues at security, getting half-undressed and taking shoes off, half-unpacking my bags and repacking them, being sent back because my ziploc bag is supposedly too big even though it’s smaller than the dimensions they show at security, then waiting around another 40 minutes in a shopping mall with runways attached is not fun. Since I always nearly always have to change planes, I get to do it twice, usually with a much longer wait at the intermediate airport (that’s not so bad if it’s lunch or dinner time and the intermediate airport has conveyor belt sushi – but I’ve been though the security rigmarole once – why do I have to do it again? In the USA you don’t – once you’re airside you stay airside when changing planes).
The airlines also won’t take me to places where the Auster will.
20 minutes, assuming no hitches, less if fuel is not needed.
I tend to do all the planning before, if it is any distance or something new, so when I arrive it is a matter of a pre-flight, get in, load the FPL, taxi clearance and go.
Obvioulsy with passengers you want it to be an “experience” so slow the whole thing down accordingly.
Although the timing for the pilot can be quite long (though as an owner, I reckon on about 20 mins from arrival to engine start) one big advantage can be for the passengers, who can be briefed to arrive a little later and they can then literally walk from the car to the aircraft in about 3 minutes (5 if they want the toilet) and off we go.
The speed of departure in my case is greatly helped by @achimha, as I have preloaded the route on an SD card, and by SkyDemon, which has everything ready for me.
As a student pilot I’m still somewhat slower more careful with the walkaround and checks. And of course I also depend on the instructor, who is often taking time chatting to basically everyone on the airfield debriefing the previous student before he turns to me. Otherwise I guess I’d take only 10 minutes, as everything is convieniently close at my home base, there are no security measures to speak of (not even a gate with some kind of lock) and refueling can be done straight across the taxiway on the other side of the hangar. All is done on our own and without asking anyone for prior permission, as our club is one of the main users of the field and the FIugleiter are some of the most relaxed persons in this business (and widely credited on eddh.de for their helpfulness)
If you have time to spare, travel by air…
The 90 mph Super Cub encourages a slow food approach, and by definition we are talking good VFR. The steel push bike (in England we call bicycles push bikes because when they were invented they were pushed – go figure) takes approximately three hours to carry me from North London to Andrewsfield, including a coffee break at Woodford Bridge. Personal wattage is then consumed by very carefully moving between three or four aircraft out of the hangar ahead of me. Using the aircraft more frequently would shorten this, as it would sit in pole position. I then politely move my hangar neighbours back in the hangar. There is then around an hour of pottering around while I refuel, and do the walk around. The Super Cub lets all its nuts, bolts, cotter pins, hang out like a generous person in the summer of love – so a good pre flight means checking they are all there!
The local engineers look after the 66 year old Continental, and it always starts promptly on the first hand prop after the left mag is placed to hot (priming having been done cold). Taxiing is at a leisurely pace, slightly faster than zimmer frame speed, and some time is gained on the pre take off checks – lets say even if you repeated the flow pattern three times the checks would be completed in a couple of minutes.
Typically it will then head off to either Hampshire or Yorkshire to visit friends – and compared to the steel push bike, 90 mph feels like warp speed.
Returning it is more efficient – it will take up pole position in the hangar, and then its a matter of heading back into London into the prevailing wind, usually adding a good 30-45 minutes to the journey.
Door to door we are talking around twelve hours, with possibly around 250-300 flight miles. Bombing up the M11 in the VW1300 (ie 50 mph) saves around four or five hours.
Hahaha. The the champ float plane was a bit like this… drive to the airport, hitch-up the dolly. Tow the aircraft to the fuel pumps (or conversely fill three or four jerry cans). Tow it back to the ramp, preflight it (perhaps even putting in some new self tapping screws which have rattled out of the trim during the last flight), pump out the floats. Put the aircraft in the water and move it to the dock. Pull the car and trailer out, park it. Get in the aircraft and start the engine (occasionally hand propping while standing on the floats!), taxi and depart…
Depending on the day, this could take ages…. not to mention washing it down afterwards if you were in salt water.
Then there was a trip where I was cruising at 60-80 mph in a 45-50mph headwind. If I slowed down (the plane can fly at 40mph), I could have seen the gps pointing in the opposite direction to the compass! I wish I had taken a photo; however, the gps was stolen shortly after that and we never replaced it. The airspace in much of Canada is not so complicated and it was back to the pencil line on the map with quarter and half way hash marks. Just make sure there is more than half a tank of fuel, when you are at the halfway mark.
This type of flying is all about the experience… the time is irrelevant, you are in for the day! I would often toss a sleeping bag in the back… just in case you were in for more than one day!
Just going to make it before dark!
Landed.
No rush.
Not going anywhere soon.
Killing time.
