When an installer replaces a window in a sheet rock return as replacement, i see many installers installing the replacement window sheetrock to sheetrock and then using some sort of quarter round trim if that makes any sense? Is this acceptable? I figure since sheet rock butts up against a 2 x 4, there wouldnt be that " empty gap" you could encounter on a wood return where original frame would meet the 2 x 4 ?

I guess with an aluminum window with sheet rock return, there is just a nail flange with no original wood frame that you guys normally see in a xommon wood return?

I also see some guys installing from the outside using a nail flange but still doing replacement in a way. My question is how they do this since the jamb depth of the new window would be deeper, 3 1/4" . Or is the jamb depth on a new construction vinyl window only 2 1/4 jamb depth thereby eliminating the need to cut the sheetrock?

I always assumed the sheet rock would need to be cut when doing a replacement with a nail flange. I guess yiu guys can use a utility knife/ box cutter to do that without causing the sheet rock to crack?