It's an individual thing, though I've never heard any experienced player vote for three.
A "Courteney" is a set of three evenly spaced custom wedges, highly recommended here in addition to the iron set's PW..
Four wedges (i.e. PW from the iron set and three individual wedges) give more choice of yardage selection in the lower range of approach shots, Including the punch yardages, you get seven or eight (1) 100% shots from different distance. granting high precision shots.
(1) if PW punch and top wedge full shot differ enough
It's obvious that the choice depends on the PW's yardage, thus on the iron set available or planned. With a shorter iron set, only two wedges may be sufficient. The yardage ranges in a triple set are about
50/60 yds for the shortest one,
75/85 yds for the medium club,
95/105 yds for the long wedge,
providing punch shots of approx. 80%.
My choice, fitting to a 110 yds PW, is 50 (punch 41) - 77 (63) - 100 (81) yds, with mid quality (lvl 40) at the low end and high quality at the top. The latter minimizes ball roll - "darting" and backspin zzzips are fun!
I sacrificed my hybrid to get the space, and once tried to figure out how to swap 3WD and hybrid for different courses. Alas, I have no strategy yet - advantage 3WD most of the time.