I think some of us in this thread might actually be on the same page but not communicating with each other for some reason.
In the US anyway, when we start new students, we stress the use of written checklists for very sound reasons that have been proven by us anyway over time to be an effective way to acclimate them to a new world that dictates a simple premise. Airplanes have critical items that if not selected or checked in a specific manner before or during flight, the result might very well NOT be the same result that the student might expect to experience in a car if they forgot something or didn't select it properly.
Basically, it's for this reason, and to engender in a new student good solid habit patterns that we introduce them to the written checklist.
There is a natural process that in reality dictates when and where a pilot having moved on up from the student stage will be using a written checklist and where a flow pattern is indicated.
There is a big difference between single pilot and and crew operation when it comes to checklists and how they should be handled. There actually is no one single answer that fits all scenarios.
For a pilot flying the same aircraft day in and day out, a natural flow pattern is indicated. Hell, I flew the same P51D all the time for several years. We had a written checklist for the airplane but knowing it like I did, I developed a flow pattern that went through both the exterior and interior checks and did them each time, every time, exactly the same way without the written checklist.
Conversely, when I moved over to the F8F-2 for a few flights, I used the written checklist each time I flew this airplane.
So it's not a 'written in stone' thing with checklists.
I've never been a member of a crew in a 121 or 135 operation so I won't even comment in that area, but if asked, I would say that when it comes to flight safety, as PIC you do whatever it takes to operate the aircraft in a safe manner.
Dudley Henriques