I would like to know this as well. The only "trick" I use is farm keys with different classes. For example my DHs can get higher keys in less waves and they happen to hit 35 keys on the wave 6 or 7, all the time, 40+ on next wave. So if I want 35s, I do trials with them and leave at whatever wave needed. Barbs get 38s more consistent, so if I need those, I just switch classes.

They only other thing I can think of is removing some DPS, using other skills so u do less damage. Trials are such a boring part of the game and the whole concept is just stupid. Do bounties to get Rift Fragments, then regular Rifts to get trial keys and then trials to get GR keys. Who was the "genius" who designed such a stupid mechanic????????

Anyway, just remember to use the key switching trick or whatever is called so u dont use them too fast. A lot of multiboxers don't know what it is or how to do it and they waste a ton of time with trials. It's a huge difference and completely legal. Instead of doing 10 trials for 10 GR runs u do like 37 runs i think with the same 10 keys.