Staggered terms for board members are permitted under Corporations Code Section 7220(a):

Bylaws may provide for staggering the terms of directors by dividing the total number of directors into groups of one or more directors. The terms of office of the several groups and the number of directors in each group need not be uniform.

Bylaws created by developers usually establish the term of office at one year, which requires all directors to stand for election each year. Many associations amend this provision to establish two-year staggered terms so as to create stability and continuity on the board. Unless bylaws provide otherwise, staggered terms also apply to appointed directors.