Some brands aren't as good for retaping. I use ABU Super Dry Kids and Bambino Classicos. I previously used Dotty.
littlelolikat always says the tapes should be on your hip bones in her videos, and that's what I aim for.
Absolutely retape if you're diapering yourself. I find for a snug fit I need to lie down and tape them first, then stand with my back pressed up against a wall just to adjust.
I think increasingly I just dislike double tape diapers honestly. The bottom ones always pop if I move around too much.
But yeah just adjust so the leg holes are reasonably snug. Otherwise they'll deform when you sit. You want to be careful when you're sitting anyway, you're effectively wearing a sponge, compression isn't gonna help.