Is it necessary to make a new version release every year ?

Since some of the improvements are marginal, can these improvements be build-updates? Archicad has made significant progress since releasing 21 with the New Stair tool being the subject of that upgrade. I do know it is a marketing strategy for profit and sustenance, but paying $700 x 4 for a small office like ours is not feasible yearly just to update to a new version in such a small market.