Hi Nick
I update the main zip at the same time as I do the normal zips that I post here, which is when I have collected about 80 or 90 new/revised logos. The frequency mainly depends on how often I get long lists of demands from Ian and ACW ;-)
I guess that most users dowload the main zip just once, then use the update zips to keep up to date. Personally, if I wasn't the "zipmaster", I would download individual logos only when I thought they might stand a chance of appearing on my system.
Hope that helps.
Rod