You hear all the time in ancient history about cities or fortresses being besieged for a year, or two years, or even many years such as the sieges of Tripoli or Carthage or Drepana. I'm wondering, what would the attacking armies do that whole time? Did they just set up shop, built a little town and wait the defenders out, or were there usually active efforts to break in going throughout that whole time?
I know it's a tough challenge to break through a fortified city, and there's always the option of just starving them out, but it seems strange to have an army at your disposal and not be actively using it to try to win, whether through attacking head-on or infiltrating or tunneling or bribing or even just throwing flaming arrows and stones over the wall to make life hell for the citizens all day every day.
But on the other hand, it's also hard to imagine that active, daily efforts like that could be resisted for years at a time. Even an army without major siege equipment could set fire to the city with arrows or flaming debris shot over the wall, or even build a ramp up to the wall itself, like at Masada or Tyre. Hell, it seems like just lobbing a big rock once or twice every couple of hours would knock down a gate or a wall in less than a year... Obviously, that kind of thing would be difficult and expensive, but surely it wouldn't compare to the expense of keeping an army in the field indefinitely?
So were multi-year sieges characterized by long periods of inactivity, where the attacking army basically just loitered outside the city? Or were most sieges characterized by consistent activity throughout, and the length merely speaks to just how tough it is to break through city walls?