Heavy Tank call ins need to be delayed. I would suggest making them cost more fuel if Tier3 and/or aren't purchased. Or make each subsequent call in cost more fuel so they can't be spammed.
What would also help is if Soviets got a big reduction in the fuel cost to Tier3 and Tier4 after having built the other one, so tech swapping from Tier3 to 4 is actually possible so Soviets don't HAVE to depend on a doctrine specific late game tank call in.
