I don't do a lot of diving below about 40m (about 130") so I rarely use trimix, and because I often dive in places where helium is relatively expensive I usually don't use it in the 40-50m range (to around 165" I guess). However, as others have said, current and cold and visibility and whether or being in a solid overhead environment: those all tend to magnify my narcosis. Last month I did ap week of wreck dives at 50-54m depths and was glad to be breathing trimix the whole time. I've done dives like that on air, but it sure was nice to have all my wits about me, especially during tight, silty penetrations with spooky war grave stuff lying around.
That said, a week on trimix was a splurge for me, and I do get my back up a little bit about the socioeconomic class presumptions of some divers who willingly embark upon quite challenging and quite risky dives in terms of deco and oxygen exposure and restrictions, but who get all uppity about working class folks like me diving air. You choose your risks, and I'll choose mine, and
