Battle Tanks game length.

[IlPalazzo]

Attacker dont mean "winner". The game also proceed while you attack and they defend. If you want to win game by capturing CPs, simply write -cv.
And there are lots of ways to attack a base and destroy factories while your enemy will be optionless (of course if you are stronger in that phase).
-Buy a factory or two and place them near enemy base.
-Buy Siege Pack or ATC. And let your mortars destroy towers.
-Spam abilities that can hit buildings and preffer tanks that can chop buildings down.
-Buy Troop Center and send waves of creeps to cover you or simply send mortars while you make your enemy busy.
-Buy an Infernal and make suicide jumps.
But if you continue your normal game play and do not get into siege mode , it will be a combat in front of enemy base and that wont give you any advantage (unless you sweep all the enemy and attack defensless base, which will be rare).

I agree, sieging is one of the most interesting part of the game. Again, I was merely responding to the notion that seiging might make the game too long. I don't expect the DevTeam to completely neuter the siege attacker/defender dynamics, but if they feel that it is TOO favorable to one side or the other, they could start by considering the placement of their buildings/terrain/weapon ranges.

You do bring up good suggestions on how to siege, but you have to remember that buying a factory/troop command/mortar team/infernal costs gold, which places the attacking team behind if they are required to buy an item for a specific purpose. If balance is an issue here, we have to ask "Is it reasonably possible for the attackers to invest 2,000-5,000 gold into this 'stuff' and still be on-par (or even more advanced) in terms of tanks/weapons/hulls/etc. to the defending team?"

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?

And it is supposed to take a lot time because of game dynamics. Just killing a guy for 5 times and getting a 2x better tank is called "-hb"..

...So ... I have to kill a guy 10 times to get a 2x better tank?