No tolerance to speak of ime, took it daily/near daily for 4 years straight myself, it always works lol. The main things i've found that people should take into account are dosages, timing between the Harmalas and DMT, the plant quality, and the brew quality, also making sure to take it on an empty stomach as food or sluggish digestion can throw off absorption. So long as the plants are good quality, the brews are of a thoroughly good quality, the dosages are known, and the timing is right, it'll work. I recommend taking the Harmalas first, waiting 30 minutes to an hour although i recommend an hour, and then taking the DMT. Often times when this stuff doesn't work right it's because the DMT wasn't properly activated, and even a low dose of DMT like 1 to 2 grams of Mimosa can be noticeable ime. It's relatively common for Aya to not work for people sometimes, especially as it's traditionally consumed (both plants combined together and consumed at the same time), which consuming it as it's consumed traditionally "can" work, obviously, but it's not as efficient as predosing the Harmalas, waiting for them to inhibit gut MAO-A more maximally, and then taking the DMT. And ime even a low dose of Harmalas can orally activate DMT, so i wouldn't say it's a dosage thing, i'd say it's either a timing thing or a plant or brew quality thing. Brews especially need to be done thoroughly and even then filtering/cleaning things up can also reduce potency sometimes if one isn't careful.