at regular intervals (adverb) frequently: commonly, repeatedly
Sinonime: act for, alternate, answer for, back up, be in place of, change, commute, cover for, deputize, displace, do the work of, double for, fill in, fill in for, fill one's position, go as, proxy, relieve, replace, serve in one's stead, spell, stand for, stand in, stand in for, sub, supersede, supplant,
supply, swap, swap places with, switch, take another's place, take over
Antonime: infrequently, not much,
rarely,
seldom, uncommonly