I have tried a few with Dye-sub and using
JPSS.
The Sublimation came out better but you need a big press as the paper does not stick and will move if you try to press in sections.
JPSS will stick to the shirt and it is easy to press but the lines where the transfers meet is just visible up close.

Trying to do an all over with
JPSS, I had trouble peeling the transfer and had to re-heat the shirt several times to get all 8 sheets of 8 1/2 X 11
JPSS off of the shirt.

The best way to do it that I have found is to try to have sections that do not meet on the second or third sheet. Just several smaller pressings comes out OK.
I use a carrier sheet to line then all up and I use a Teflon pillow and make sure that I cover everything with a Teflon sheet.