This is me too... I do a heroic TR, then 2-3 epic TRs, then back to heroic... During the 2-3 epic TRs, I barely repeat anything. There's a ton of content in the 20-28 range, especially if you have reset all explorer/slayer areas.
Each TR takes me about a month...
So I run a heroic TR, get up to epic levels, run 2-3 epic TRs without repeating a quest, then heroic TR again... It is literally at least 3 months between each repeat of a quest for me. This game is not grindy at all with my playstyle... I change my character every heroic TR to something different and new, and the quests are not boring because I'm not repeating the same 30 best xp/min quests over and over every 5 days.