C172N checklist

[flyinkiwi]

My 2c on the subject.

1. I have never flown a 172 in any fuel configuration other than tanks on both. Thankfully I've not needed to cut the fuel off (yet).
2. My opinion is that the OPs flight school introduced tank switching into the 172N checklist to get their students into the habit of fuel management for when they fly other types which may not have a Both setting in their fuel systems. Whether or not this is a good idea I'll leave up to you.