I agree,but also not agree,yeah i know ..but look at the Sanatorium server,rarely i've seen it without players ,and it is there for very,very long time.There are many players ,always someone new.and i can play Sanatorium every few days without problem,not boring.
Changing map once every week is surely too fast ,that way only few players can say they played it and did easter egg.2 or even better 3 weeks for 1 map ,is much better,most players can find time to play it ,and some can even say it's getting boring :).