Monoliths and Boss Farming

I'm starting to get a little jaded on monolith boss farming since it takes forever to get back to the boss. I'm hoping someone can chime in to point out what I might be doing wrong or provide some tips or tricks.

Essentially I am power-running echoes, ignoring all mobs, attempting to complete the echo's goal as fast as possible. This continues if I can increase corruption until I fight a shade of orobyss, and then I run all the boss quests.

I'm farming normal Reign of Dragons which is maxed at 50 corruption and has raised the area level to 90. The difficulty is definitely manageable, but even though I'm no longer needing to spend time to fight the shade of Orobyss, the turn-around time to complete enough echoes while rushing is still about 25-ish minutes.

It kind of sucks having to do all of this, fight the boss once in 25-30 minutes and then have to repeat. Am I doing something wrong or is this just how it is? I'm not expecting to farm the Emperor of Corpses every 5 minutes, but more than twice per hour would be nice...

I'm level 90 with maxed elemental resistances, but I have 2/3s physical, poison, necrotic, and void resistances. The normal monoliths even with maxed corruption are basically a cake-walk; I'll only die if I'm being super negligent and engaging an entire screen full of mobs.

Obviously, my top priority is getting to level 100, but I wanted to try and maximize farming at the same time...

*note: before any buffs, including shrines, I have +50% movement speed, so with all buffs and shrines, I zoom pretty quick.