I will never argue against the reference to a checklist (providing it is not interfering with flying), but I certainly use a "flow" check method myself. For most single engine types I fly, the flow will be the same, with the possible differences being cowl flaps and propeller setting.
I don't remind myself checklist style, about the position of the wheels on fixed gear planes. I do, however, say out loud to myself (and my 9 year old daughter, who tends to repeat it now) "wheels are down for landing on land", or "wheels are up for landing on water" as appropriate. I have set upon this as my flow check for any retractable I fly, as it covers every type of retractable I fly. The basic "wheels down for landing" is really bad for amphibian landings on water - so I don't do it!
Happily, most certified aircraft are designed and approved so that forgetting most checklist items is not immediately critical (aside from the obvious landing gear selection). Any critical thing is going to make itself known fairly shortly, if it matters. Not to say that's okay, or acceptable, but should not cause an accident. Examples of this would include not selecting fine for the prop before initiating an overshoot - it's not good for the engine, but you'll probably notice before it stops in anger.
Flaps selection/mis-selection is always a hot checklist topic, and yes, the odd time I get airborne with a flap setting other than I intended. Happily, in all but the most critical short runways, this is manageable. The lowly C 150 will touch and go, or overshoot, and climb away, with full flaps out. It is not stellar, and you'll remember it for a while, but can be safely done.
Worse than entering the next phase of flight with something wrong in the configuration, can be failing to maintain control of the aircraft while you suddenly realize it, and change things. Your attention is drawn away from flying by (a) something surprising you as being wrong, and (b) fixing it. If possible, leave it as is, until you are safely established in the next phase (climbing away steadily hopefully). I was right seat to a pilot who completely forgot to fly a Piper Arrow right after breaking ground, because the tower called to say that the Nav lights were not on for a dusk flight. Not good, but not worth crashing over! Wait until things are stable before diverting attention.
When I fly twins, or very advance singles, I use the paper checklist. I would rather do that, than explain why I had not after something went wrong. But that's my personal comfort level.
Yesterday I went flew up to maintenance test fly a very rebuilt C-206. It was barely VFR flying my very well known route, but I got in okay. Once on the ground, I explained to the client that despite real operational pressure, I would not be flying the 206. Weather that poor was not the place to be with an aircraft on a test flight, particularly as I was expected to stall it - not with a 1000 foot ceiling! I told the client that while still on the ground, I could see two Swiss cheese holes lining up, and I had not even got into the plane yet. My client agreed. I like to think that I maintained safety, and set a good example for my client's pilots. I test flew it this morning, and everything was fine....
In my experience when I screwed up complacency was manifested in doing things in the cockpit too fast. Fast hands in the cockpit has bent a lot of metal over the years and forcing yourself to not rush is IMO a good way to avoid being complacent.
With respect to checklist I am with PIlot DAR. Flow checks are the right way to do most things in a single pilot environment. When I fly my Nanchang CJ6 I never use a written checklist for normal ops. Instead I have a left to right flow that covers every necessary check. In this case I am use the physical knobs, buttons, switches, and levers as my "list" of things to check. A consistent order ensures that I don't miss anything.
One huge problem IMO is the near universal tendency of flying schools to use the checklist as a learn to fly tool instead of its true purpose which is only safety of flight. So every thing on the checklist should be something that will significantly and immediately effect the safety of the flight if the item is missed. Using this philosophy I recently rewrote the checklist at a school I do some teaching at. The new checklist was 1/3 the length of the old one and followed a consistent and logical flow for all checks instead of jumping all over the cockpit.
