Battle Tanks game length.

[IlPalazzo]

which places the attacking team behind if they are required to buy an item for a specific purpose

This is a problem I see often.
People seem to forget that it doesn't matter how much your tank is worth, or what items you carry - if you have won the game.
There is nothing wrong with selling some standard dps to get those siege packs up, and end the game - who cares if they get an extra three kills? Money is of no use to them if they are dead.

I have had numerous games, where I have had to sell some items for sieging equipment and factories, and - as long as your allies are paying attention, it is totally worth it.

Maybe I should try using those items more often, but I don't use it mostly because I see it as a risk... If the opposing team breaks the siege then the Mortar Team and such becomes essentially useless, which places you even further behind than if you bought a weapon/hull.

It should also be noted that usually the attacker has taken down a few towers belonging to the defender, this effectively reduces the 'cost' of the siege items, since you get some fast, extra gold from the additional buildings destroyed.

I know, but is this cost 'reduction' enough, too much, or too little?

As I stated above:
"Currently there are 7 Towers in the middle lane and 5 Towers in each side lanes. Since I don't know how Tower bounty works, I don't know how much gold that gives to the attacking team. Is 17 towers enough to initiate an effective siege? Should it be? If not, how long should the attacking team be waiting before they start attacking?"