If you have more than 5 tanks, clumping can be more advantageous than spreading because more tanks are attacking the same target when they come in range and with that many tanks this means targets will die instantly before doing any damage, this is good vs bioball and gateway units and spell casters because they won't be able to get in range without taking heavy losses, especially when you block with your mobile units.

Unlike SC1, SC2 tank AI is very fast at knowing when a unit is dead so they don't waste shots. This was one idea that was brought up about nerfing the tank on the forums, to reintroduce the old AI but blizzard opted to reduce the damage-- thus more tanks in the same place means shot's aren't wasted as compared to SC1 and your still doing massive damage at a far range and with splash damage.

Chances are, if they try to close the gap vs tanks and waste aoe on the tanks as opposed to your infantry, your army will come out on top. That's the idea.

If you have more than 5 tanks, clumping can be more advantageous than spreading because more tanks are attacking the same target when they come in range and with that many tanks this means targets will die instantly before doing any damage, this is good vs bioball and gateway units and spell casters because they won't be able to get in range without taking heavy losses, especially when you block with your mobile units.

Unlike SC1, SC2 tank AI is very fast at knowing when a unit is dead so they don't waste shots. This was one idea that was brought up about nerfing the tank on the forums, to reintroduce the old AI but blizzard opted to reduce the damage-- thus more tanks in the same place means shot's aren't wasted as compared to SC1 and you're still doing massive damage at a far range and with splash damage.

Chances are, if they try to close the gap vs tanks and waste aoe on the tanks as opposed to your infantry, your army will come out on top. That's the idea.