The "board goes behind it" thing got me too. I spent years putting the board in front of the book because that's just how I saw it done at my local shop back in the day. Went through my old X-Men run from around 2010 and found these little dents down the spine where the board edge pressed in every time I slid one in. Nobody ever told me it was wrong, the shop guys just watched me do it and took my money. Now I re-bag everything and cringe.

Learned this the hard way too. Tired people sound like robots, it's just how it is. Stop playing detective on calls and just be nice. Works way better.

Harsh notes are the ones that actually fix your work. Good on you for doing the work instead of getting defensive.