The "town square" while taking cities

[conon394]

T. Livius

For Motya see Diodorus 14.52.5
You can find an online translation at Perseus: http://www.perseus.tufts.edu/cgi-bin...=Diod.+14.52.1

For Plataea see Thucydides 2.2 ff (you can find an online version at the Perseus site as well).

On Pyrrhus, turns out he is not an isolated case, but rather the norm. If you look up Thucydides and his description on Plataea, you find tile chucking women and slaves again playing a pivotal role in the defense of a polis....

Edit:
3 counter examples however do not necessarily invalidate the relative accuracy of your original post. But since (as a defender), you cannot build either regular or emergency interior wars (or build up the height of your walls), or counter mine, or have tile tossing women, I think a timer is a fair abstraction. I would give the AI a longer time period then the human player though.