Here's another thing, if you actually know what you're doing you can fight stuff way above your level, went from 17.4-20, which includes hell level 19 that takes double xp in 4 hours tonight tanking bugs that are level 24, and everyone was below 24. if you fight stuff like 3 levels below you, it would take way way longer to level. a lot of it is knowledge and not splitting exp 6 ways on easy garbage that's below you. you could duo or trio stuff that's 2-3 levels below you'd level faster than doing it with a full group.