The thickest of transplants will "dense pack" 50-60 grafts per cm^2 at the hairline and even less in other areas. This creates an "illusion of density" that will look ok under certain situations and lighting, but will never match the aesthetic of a full head of native hair.
Unless you're a freak of nature, you likely won't have enough donor grafts to cover a slick bald scalp, unless you are willing to settle for a conservative result, i.e., recessed hairline and sparse looking, overall see through head of hair. And if you're NW7 you can usually forget about transplant being an option at all.
Most of the guys you see with a complete full head of hair after a transplant already had a decent amount of hair left and just had their bald areas filled in, while being on medication to maintain native hair