OK, lets take a campaign mission for example. I've done only 10 missions so far. Every time I take 6x AGM65D, 2x GBU10, 2x AIM-9, TGP and 85% of fuel. In such configuration I am able to reach the target, destroy it, find and destroy extra targets market by JTAC, RTB and still have plenty of fuel on board. Why should I bother about optimum cruise altitude, combat radius and/or bingo/joker fuel levels?
Don't take me wrong. I am not saying all these drag/performance calculations are useless, just want to understand how and when virtual pilots use it in DCS world.