When you make the transition from being a raider to assuming the role of raid leader or just wanting to be a better raider there comes a macro “big window” view you have to take into account.
As a raider you only care about your damaging/healing/tanking abilities and how they interact with the raid. Always running the recount/skada/combat parsers and where you’re at on the meters. As a raid leader you have to take a macro “big window” view towards the raid as a whole.
Double potting (using one potion pre-pull and then another during combat) is a good habit to get into even on farm night. Kill the boss faster and move onto the next boss faster. Now take that and multiply it by 20+ people because as a raid leader you now have to view it at a macro level.
Cheap enchants/gems/flasks are another trap. The blue 630 item level piece isn’t “worth a good enchant,” but on a macro level it’s the best gear you have and if everyone thinks cheap is okay because the gear isn’t worth it then on a macro level you have an issue. Now take all those missed stats and multiply it by the number of raiders. The math starts to add up.
On a macro level you want to kill or practice on as many bosses as you can during your allotted raid time. Allowing single or no potions and cheap or no enchants/gems/flasks isn’t helping towards your goal.
Be a good raider/raid leader: Think macro, not micro.