I use reduced power settings whenever I fly the La-7. It's biggest weakness is lack of fuel on full power (to say nothing of WEP), but its biggest secret is that it floats like a glider when you dial it back. You can get clear across the map on reduced settings. Typically I set up a gentle climbout on reduced power to optimum cruise altitude, cruise to where I'm going, go to full power to climb to combat altitude, have the fight, and then I have enough fuel to go home on full power, just in case someone wants to chase me. That's assuming I don't get shot down first.
So if you want to see people doing more realistic fuel/throttle management, you either have to make the missions longer, or increase the burn rate so that more planes are in the La-7s shoes, with marginal reserves for typical missions. Even so planes like the 51 with its huge range will just carry more fuel and fly full throttle.
And BTW - even if you just keep the throttle open all the time, if you just autoclimb from the runway to altitude you're wasting both fuel and time. You'll get there faster with a bigger reserve if you climb gently to the altitude where you get the best tradeoff between TAS and climb-time, cruise at that height till you're where you want to be and do your final climb there, when you're lighter. Otherwise you're just burning fuel to lift fuel, and wasting time doing it.