Indeed one will need high SOP/CRM standards for single IFR operations but that implies one is using his aircraft & systems to the max performance to it’s tight minima? and maintain decent flying currency?
Disciplined routine & high standards goes with low margins & max utility? take the go-around on unstable approach parameters (1/2 scale & -1kfpm), how much that’s relevant for someone who only flies SEP on ILS in 1500agl clouds and 10km visibility?
I can’t blame someone who was told to only fly 800ft agl ceilings to have no routine & drills at all, he can do safely without 
One of the advantages of the MPL type of training is that cadets learn CRM in the cockpit quite early in the program. Like all skills it requires training and practice. Arguably formal CRM/MCC is useful training for single pilot IR operations – in fact the old single pilot AOC ops would have recurrent CRM training. The preparation for top of descent briefing, which in the real world on a short sector will take place before top of climb, requires a disciplined routine. Am thinking of the CAA video posted by @Peter, where absence of disciplined routine seemed to be the norm.
Some airlines have various gates on the approach, where if checks, speed and configuration are not established, the SOP is to initiate a go around, not just at DA. In the video by the CAA, just dialling in a rate of descent above 1,000 fpm on the localiser would have prompted a go around call, let alone being out of CDFA limits. Unfortunately the EASA IR remains highly choreographed and the two go around are at DA/MDA. The candidate if he decided to go around before, because he judged he was unstable/at limits (outside speed limits, 1/2 deflection, 50 feet on CDFA), would be rewarded with a partial for that element of the test. For better or worse, MPL training has a greater focus on stable approach criteria and going around early if conditions/situation require it.
This recent breakdown in CRM will no doubt make the CRM recurrent training rounds:
https://www.gov.uk/aaib-reports/aaib-investigation-to-boeing-737-86n-i-neot
When I fly with another pilot and I am in the RHS, I offer to change Radio frequencies & Squawks.
I make sure that the other guy knows he is PIC, but will assist him if asked.
If I think the PIC has forgotten something or is doing something wrong then I dont hesitate to speak up.
If I am PIC and with another pilot in the RHS I would appreciate them doing exactly the same for me.
This video is a great example of CRM during a low IFR approach at night (in Texas). PIC giving work to the LHS person, himself a CFII. The CFII remaining in what the PIC asked him. You can see at the end it made the PIC sweat !
I think even in the cruise, with the autopilot on, in perfect weather, and cleared on a long direct, just about everyone would tell that passenger to be quiet
Someone (non-pilot) told me one day to shut up while flying as I did not seem for him as able to do both at the same time, that was early days but this weakness seems to persisit…
This is a really good video on “CRM” when flying with somebody else – in this case a non-pilot. It is 25 mins but is worth watching in its entirety
The amount of interference from the passenger in this video makes one cringe, but I had a flight with a CPL/IR pilot in the RHS who was even worse than that and could not stop talking.
Funnily enough the guy whose name appears at 13:15 did my initial JAA IR test 
He was excellent; probably the best examiner I have ever flown with.
Emir as a point of order i dont think anyone is playing big boys games, in fact quite the reverse. I have consistently said this isnt crm but task sharing, and i am bemused that possibly some contributors think it is, as slightly worryingly one is left wondering whether they are confused with what they are doing.
@dublinpilot you’re quite right. It was my fault. I started taking decisions and passing them over the radio before consulting PIC. It was a good lesson on what not to do. We were not prepared for the situation and both panicked a bit. We don’t want it to happen again, so we’re doing our own radio now and consult if we want, or not. It has to be clear who is in command.
It’s interesting how people like to play games and different roles. But that doesn’t have anything with CRM. Handle transponder? Asking before touching? Read-backs of radio calls without procedure of executing and confirming tasks in cockpit? Sorry, don’t be offended but this is joke. You like to play big guys in simple aircraft. Ok, feel free to do it if it makes you happy and makes your flying more fun but don’t mix it up with CRM.
