Make 10 T4, for it to be coherent it needs to have taken like 5-7 minutes of mass generation otherwise it's an all in gamble which already denotes this isn't great play. For that to happen, you need like 800 mass income per second across the whole team being invested into T4 at 28,000 mass cost per T4. It takes about 2 minutes to cross the map, in that time the enemy will have built up another 4 or more T4 as they should have the mass lead due to your earlier investment in 10 T4.
This problem continues to scale up, it's why this is a bad move and it's why game enders exists.
In this, I have not taken into account all of the very mass efficient counters to potential attacks like this ie nukes, air, tmls, arty which a 10 T4 attack would need to account for and saddle the mass investment with superfluous costs which the defender does not need to worry about. Accounting for that, a defender could also now have made 6 or 7 T4 by the time this 10 T4 attack actually begins reaching to attack a game-winning target.