I think Blizzard need to bring in multiple save points where keys don’t deplete below a certain number, this way more people can use it because the vast majority of the player base isn’t getting 2850 rating.
Mythic+ 8 first save point if you can time all 8’s key never depletes below this.
Mythic+ 10 allows for easy Mythic vault farm every week if you can time all 10’s.
Mythic+12 for the higher key pushers like the Top 1% of Mythic+ players who can time every Dungeon as a 12 then it doesn’t deplete below this number.
This is also per Character not across your whole Warband or it would be much more alt friendly.