By far the easiest & least stressful way to unlock brand new tech tree is not to play these vehicles at all but rather collect vehicle blueprint fragments from Daily Mission (I'd re-rolled missions unless its reward was bonds or blueprint fragment) rewards.
In these past days I was getting about 3 fragments per day and since there are only 4 vehicles in brand new Chinese Heavy Tank tech tree (Tier VII to X) it took only 13 days.
necessary vehicle modules: 121000 Free XP
Daily Missions: 35 vehicle fragments (1 fragment: 2x; 2 fragments: 6x; 3 fragments: 8x)
Tour of Duty: 3 vehicle fragments
Another advantage to this method is that it's significantly cheaper than similar options…
- 'Free XP only' route would cost: 571000 (+ 121000 Free XP)
- Universal/National blueprint research would cost: 408 Universal blueprints + 126 Chinese blueprints (+ 121000 Free XP)
