I teach the preflight as a flow you do everytime with specific things you check each time with the checklist used to verify you did it .Imo, the read and do checklist method for a preflight that is widely taught is poor technique. It gets them buried in a sea of words and has the potential to make them lose the big picture- I prefer for them to have an understanding of what it is they are looking for and have their eyes moving around the airplane rather than trying to remember where they are on an overkill 9 page checklist that includes stuff like "get atis" and "request taxi" or even "key-turn to start engine". I'm not advocating ditching the checklist, I just think it should be used as a checklist rather than a do list.
This is how I teach it. A flow and verify with the written. I do it in 2 parts usually though. Inside flow then checklist, outside flow then checklist. In our Cessna 172R with the G1000, there is a lot more to check inside than most light piston singles. With the Citabria, the airplane is so basic I do an entire flow start to finish, then verify with the written. By verify the written, I mean make sure I read line by line instead of skimming the checklist like I have seen students try to do...
In fact I teach all the procedures at our school like that. Flow then verify.
What kills me is the postflight.... Students blow it off. They know they've had an amazing flight. So they shrug off the post flight. I get on students when I go back and check their work and they haven't tied down the plane all the way, forgot the chocks, or didn't put the cowl plugs and pitot tube cover on etc.
One student who was particularly bad about that, I got on him a few times about it. One flight late at night before I got out, I said "I trust you're going to get everything this time since I've been hounding you about it the last few flights." The NEXT morning I get an email from one of the team leaders that my student left the tie downs off and the chock was not on both sides of the tire... After that I had a talk with my student, and it was never a problem after that. It's frustrating when it takes that much for a student to understand the importance of making sure an airplane stays airworthy from preflight to postlight...
I generally only "test" a student or check a student's preflight work in depth if it's been a while since they've had anything unusual come up in reality, or they are consistently not following the procedures and missing things.