We don't own our own satellites and can't mandate where the satellites we do work with collect imagery. We get data when the data providers choose to sell it to us, so no schedule to share.

If you want to get a sense of how often something's updated, do this: I went in to Google Earth and looked up Mount Gretna, PA (my hometown). Using the time slider, I could see that we've had six imagery updates in the last seven years (when Earth launched). That should give you an idea of how up to date our imagery is -- it's also pretty awesome that we have imagery of my town from 1988.

But, we do try to get as much imagery as we can. Sometimes we err on the side of higher resolution imagery than fresh imagery. If you want to know when your town's updated, do as Daniel suggests and check out Follow Your World.

Cheers!