I watched my friends get burned out hard on MDMA back in high school .. I learned from them, always spaced my pills initially, never more than once a month.
Later, OxyContin/adderoll got me accustomed to pharmaceutical, daily-use applications with no ill effects, a dangerous difference between different classes of chemicals.
Pretty easy to learn the lesson the hard way. your brain will hate on you so hard that you won't forget the lesson for a long while. Unless you [hypothetical] happen to be a complete idiot burnout, with reckless disregard for your numbered brain-cells ... we all have those friends

One Winter I felt like I'd shaken every last particle out of my brain after consuming too many E pills a month after blowing through an old lost-and-found oxy stash. Not as body-sick as a bad alcohol hangover, but the brain-damaged feeling lingers for days/weeks. Don't think I even touched MDMA again for years, until running into pure MDMA more recently, which is slightly more forgiving (though still not worth abusing as opposed to using).
I don't know much about chemistry (neuro or otherwise), but it did always strike me as remarkable that MDMA is so similar in all its effects to its root amphetamines, yet its duration is so much shorter, yet with an inablity to re-dose properly for weeks.
If any other drug behaved the same way I'm not sure I'd bother.
MDMA has some massive teeth it can sink into you though. it often does change lives..
In the end i'm sure i've damaged myself more from less serious substances, though I often wonder if my manual-adjusting of serotonin levels over the years had a hand in converting my lifelong depressive state from unipolar --> bipolar. a gift of sorts. I don't view MDMA as any more or less harmful than the SSRIs i was fed as a young teen, years before my first Es.
for recovery i always recommend 5-HTP / melatonin and fresh air.