What, exactly, is "Set everything up from the beginning."?

What, exactly, is "10MB of space per timeline"? How do we calculate or determine that? We are careful to monitor our budget and not call too many background updates, but lately it seems like the widget is refreshed less often and at a much slower pace, meaning the reload is called, but the widget does not update after 10, 20 event 30 minutes. I want to make sure that somehow we are not exceeding the 10 MB max, though we are showing pretty simple views.