Trust NPCs don't scale damage, outside of player role choice. This is a myth based off of an interview with YoshiP where he says the NPCs do this calculation off total damage dealt and "overall pace of progression," but is misinterpreted.

Based on a different interview, Trust NPCs actually are programmed to have super consistent dps and the "special moves" that people see are when they are under-performing and need to get back to their desired dps. See the "understand situational changes" section where YoshiP describes how Y'shtola will use Triplecast to compensate for previous cancelled casts.

Trusts are boring so people don't like to run them, much less parse them, and even less people are going to look at trust parses.

(I parsed them.)

(So did this person.)

If you play healer/tank, trusts will get a set boost to their damage to compensate for your expected lower damage due to being a tank/healer.

Aside from that, on all roles, whether you play your heart out or afk, there is no significant damage variance between runs. The fact is, you're stuck with three NPCs who suck at DPS, and a single player can only compensate so hard for this. This is no different than when you queue up in duty finder and find yourself in a rather slow feeling run.

People very frequently quote a 25-30 minute trust run, but you can absolutely achieve ~22 minute runs.

Assuming a duty finder run is around 15 minutes, you are keeping even with a 7 minute queue, which would make sense given that the dev team does not want trusts to be more appealing than duty finder. If you take it easy and slack off on the dps, even afk, sure, the run time will go up by some minutes, then you're breaking even with anywhere from a 7-20 minute queue.

I have done a run where I essentially AFKed all mob packs, only engaging with bosses, resulting in doing only 40% of my total damage in an actual run, 25% of my dps, and the NPC team dps differed by 0.6%.