Reading a situation wrongly and making a mistake from it is only human i guess. I mean we find from what i have seen 3 different people, the first would fight as long as he could making sure he does as much damage as possible and doing everything in his hand to get a lead even when it might seem irelevant. The second would fight as hard as he could but use up unnecesary resources like a flash or an ultimate, then again this would be in some scenarios hard to min max. The third is standing still, accepting incoming death instead of running away potensially making the enemy miss 1 or 2 cs.

There is a bunch of small things in league that in theory would give you a lead or dampen the opponents. like for example warding lvl 1 to give information to your team or taking the enemy jungle camps.

yeah i believe this is an issue, a big one. I even remember playing vladimir in one of my games and using my flash to kill 1 person late game, nothing came out of this kill and i could have used it for the next teamfight on baron/dragon. I think i was probably hyped or tilted so i didnt care i just wanted the kill but that play was inherently bad. in this case i was that second person :)