There is no correct "frequency", but usually on mondays there is new stuff, or one in each two weeks... But usually is just a few new parts :?
I would say to you, if you're dead right on hardtail, better do a custom order... the same for top-routed... they appear very few times, less than once in a month, usually...
(hope I'm not hi-jacking your thread Badger :lol:)