What reason did he give you this experienced chap?
I have come across lots of techniques, opinions, pet peeves of various trainers. I listen, let it pass through the BS filter, either discard it or try to remember.
I have my own things, such as not walking in to the wheel well. Don't like the idea of walking into a gas chamber of Skydrol fumes (or worse, a jet). We've had an incapacitation as a result of it. I know what the book says, but no thanks. I can spot a leak by seeing wet ground underneath instead.