4-6 times a month is a little on the heavy side for long-term consistent use, but aside from any potential risks specific to 2C-I and 4-aco-dmt (while two of the seemingly safest RCs they are still RCs, after all), I don't think there's any physiological reason it's bad. MDMA is another story, of course; it's actually physiologically damaging if used excessively. The general rule of thumb I've heard is to space out rolls by at least 2 weeks and probably more if you're using consistently over the long term.
Other than that, it's all very subjective and personal. If your use of psychedelics makes it hard for you to meet your obligations to work, school, friends and/or family then you probably need to cut back. As long as it's not trading off with something else that is important to you or those around you, I don't see a problem with tripping pretty often. The biggest subjective risk is losing sight of objective reality because you spend all your time zonked out, but 4-6 times a month is far for that level for most experienced trippers. The biggest risk there is with shorter term binges, where you try to keep yourself tripping for all or most of your waking hours over several days. So long as you have the sense to take a break for a while if new time-sensitive obligations come up or if you have a difficult experience that requires some time to integrate, you should be fine.
Personally, I rarely have a significant stock of psychedelics, so I use in bursts. I may go months or even a year or more with no trips at all, then I'll get a few doses and consume them in a relatively short time span. In general I try to keep trips spaced out by at least 5-7 days, but with 2C-I in particular I often find myself dosing multiple times a week during my usage bursts.
I use a similar amount of cannabis when I don't actively limit my consumption, and it's probably the least healthy thing I do with any regularity (now that I quit smoking tobacco regularly, anyway).
