I know some pilots who are so careful that they even use a checklist to start their car. Aeroplanes should not be flown without a checklist to tell you what to do next. Especially on downwind leg you need to read from a written checklist, because that's where you can forget to lower the wheels. If I have a passenger I get him to read the checklist to remind me what comes next as it is easy to forget. I use a checklist for the pre-flight inspection although passengers sometimes give me a funny look when they see me walking around reading from a book. But I know I am safe and that CASA inspectors want you to do that.
Some flying schools insist on long checklists but which costs money to use when the VDO is operating. I guess they have to make their money somehow. The checklists that cover all aircraft types I find the best as they remind me of things I had forgotten.
Why go to all the trouble of remembering switches and things when you can read them from a book I say.