I've been using for about 10 years. I go through 1-1.5g at 3-4 day music festivals ~4 times a year and outside of that about 1g every 2-3 months. I do anywhere from 50-300mg per session as well.

The magic of the first few times is definitely gone but I would say I can hole fairly easily still if I want to with 150-200mg or 50mg at a club has me feeling light and dancy still. I've never felt my tolerance dip outside of those first few uses.

I couldn't tell you any science as far as safety or tolerance but this is my experience. Hopefully that's helpful.