i always try to have some sort of AT before a vehicle comes out
a m20, m15, stuart or t70 can wreck you really hard, up to the point where its pointless to get AT because you already have lost way too much, and thus the game.
reactionary AT is always a gamble and it depends on your opponents playstyle whether it will pay off or not, as some people might try to push their vehicle advantage really hard and some not, opting for more conservative play
