I’ve done a couple games ftf with the latest A 3.9 where I spent $5 a turn every turn on tech. It’s not a huge waste all at once and yeah that could mean a couple less fighters in the game long term, but the potential payoff is nice. In one game my partner and I got LR air with US on turn 3-4 and were able to immediately sink a combined German/Italy fleet in sz91 because of all extra air we could fly in.
I wouldn’t consider tech on a consistent basis like that with any other country except maybe Japan/Germany later in the game once they’re around 60+ and they’re in a position where they can spare 5 bucks a turn. Maybe USSR if Germany went Sea lion and USSR has a huge stack in EPL that won’t go anywhere for several turns.