From "once in the yeare at the least" (1549 Book of common prayer) to "at the least three tymes in the yeare, of whiche Easter to bee one" (1552 Book of common prayer and following)

     This (unless I've missed something) in correction of the usually reliable Oxford dictionary of the Christian church, which since the 1st edition of 1957 right on up through the 4th edition of 2022 has claimed that "the BCP in 1549 and later editions fixed the minimum at three times a year" (1957).