Rememer that as Germany you want to take Novgorod as fast as you can after dow on Russia as it gives you the economic edge especially if the Russian player scoops up middle east territories, you should be in a position that you never have to withdraw and lose ground.
Germany can to good effect make use of a 3-4 TT purchased on G2 along with the remaining going towards Arm/Mech in Berlin to support an attack on Novgorod. Particularly if G1 consisted of a CV, DD and SS.
The Russians will probably not scramble to prevent a CR and SS from being sunk, and it clears the way to land 5 Inf, 5 Art on Novgorod the same round that the Armor and Mech arrive. If the Russians retreat out of there, you now have a ferry to move more units back and forth than the 3 you can produce in Novgorod.
All in all, I think the G2 purchase of 4 TT is almost mandatory because there will always be a threat that Germany purchases 5 more TT and challenges for London at a moment’s notice.