How to sublimate a full sweatshirt

[ArferMo]

How do you sublimate a full sweatshirt both front and back the full thing sleeves also without getting a line down the sides.

I don't mean printing the material first then making the garment up but something like this:-

[pisquee]

You either very meticulously lay out the ready-made sweatshirt out on the press, making sure there are no creases etc, although there will always be some voids, or you do have to print the raw fabric first and then cut and sew into the garment for best results.
A lot of online photographs for products of this type seem to good to be true and are just mock-ups though, in the same way a lot of mug sellers use computer generated images of their designs on mugs.