With an average team that knows what they are doing and all working for the same end goal you can absolutely get get averages out of every Task Force. Those averages equal the time spent vs Reward.
I've been playing this game for almost 20 years straight. Literally run Thousands of Task Forces from lvl 02 to 50+. Every last Task Force takes about the same time to complete every time. Just one example, the first TF, Posi 1 and 2, both should always take about 30 minutes each to run with an average team with Teleport. You may have a outlier from time to time, newb or someone who has a bad build or is just a bad player or no TP on the team. All these things will stretch out the time of course but more often then not you will not have this problem. The vast majority of those playing have been playing for years and know what they are doing.
Look, I was on the Secret Server. I know for a fact when they couldn't create new content they spent time on game balance. For years it felt like that's all they did was game balance. The game as it is now is probably more balanced then it has ever been. The last few updates have continued this trend.
So this is what it's about? Time vs Reward is absolutely the best and fairest way to distribute reward in an online video game.
I have a Def Pure Emp that I have to slog my way through Mishes with, I also have a Tank Willpower/Energy that crushes in every mish. My point is if you have a toon that doesn't crush in every mish/TF, build one. Maybe it's your toon that's as fun as a Happy Day at the Park but it just doesn't give the results you are looking for. Change it up until you find that toon that absolutely crushes the TFs so you get those averages everyone else is getting.
Happy Hunting.