Many of my addons aren't quite up to date. Some are configured oddly or have the wrong bits disabled. The result is that unless I go to the default UI, I have no XP bar.
My little paladin has no measure of how close or far he is from the next level. He has no measure of how much total experience is needed. Because of this, there is no reward from grinding. 50xp is the same as 1000xp in the sense that 20 times an unknown proportion is still unknown. Or the reverse. There is no xp/hour with no xp. Any rush is meaningless.
Have you ever seen 1% to level and done some mindless and boring grinding? My paladin has not. He is either 1% to level or 1% from having leveled. He is left with no choice but to do whatever he feels like, unaffected by any numbers telling him a better or worse way.
Adding a Time Component to Ranking Systems
1 hour ago