You spun the aeroplane without knowing where an object was in the cockpit?
Checklists are important; having a particular form of them isn't. Personally I have a generic one I use for most flying - 2 sides of A5, plus a 3rd size of A5 covering the speeds and specific drills for that aeroplane. If you look in the official POH for many light aeroplanes, you'll find a very simple easy to use checklist - it's the flying schools who embroider and complicate them to make the flying instructors feel better about not having got that flying instructor's job.
Go and fly microlights, and you'll learn to memorise them as
standard mnemonics, and they work really well. But ultimately, it's still a checklist (or action list if you prefer). Having done a lot of microlight flying, I must admit that I quite like these and sometimes use them in simpler light aeroplanes - they work very well (so long as you remember that choke off = mixture rich!)
G