For me, endgames changed when I started to constantly check my inventory. The moment you have free time, check if you need to reload a weapon, check your remaining mats, and check what items you still have. I can’t even imagine how many endgames I’ve lost by thinking I have my shotty reloaded, but there was only one shot. Or pursuing someone on high ground just to run out of mats and die from fall damage. Or thinking I had 1 more shockwave, but already used them all.
That’s definitely very helpful!! Especially the checking you ammo before a fight. I always forget to do that and it costs me the match. Pros seem to do it without thinking or even after and between every shot.