John Gill Commentary 1 Chronicles 9:25

"And their brethren, in their villages, were to come in every seven days from time to time to be with them:" — 1 Chronicles 9:25 (ASV)

And their brethren, which were in their villages
Assigned them to dwell in:

were to come after seven days from time to time with them ;
there was a new course of them every week; the old ones went off of duty, and another course succeeded, which came out of the villages where they dwelt, and the old course retired to theirs.