It all depends on play.
When I get a new pin (new to me not NIB) I do a full topside shop, changing rubbers, GI bulbs, etc, and clean and wax.
If the game is HUO after that, general cleaning takes care of things for a good long time.
If the game is routed, I try to clean the playfield with Novus 1 on a weekly basis, Novus 2 once a month, and a full topside shop every 6 months.