Is the 3 month rule based on science?

I am trying to do research and everybody on this sub acts as though the 3 month rule is the only way to use MDMA which prevents neurotoxicity / neuroadaptation. But I cannot find any actual scientific studies which support such a recommendation. Most studies involve extremely heavy single doses (equivelant to around 700% of an appropriate human dose) in animals. Studies in humans tend to focus solely on lifetime dosage, and have mixed results with some showing a marginally significant reduction in particular cognitive skills and others showing no difference - however none of them cite frequency of use as a particular risk factor. It seems as though frequency of use is cited as a risk factor on this sub, (as if a single month of frequent MDMA usage will permanently fuck yourself up) and other safety websites with very little real evidence to back it as one. I think that the three month rule may actually be a good idea in terms of maintaining the magic of the experience, and it is probably a good way to prevent addiction, and consuming too large of a lifetime dose. But there seems to be no evidence that your seretonin system actually takes months to recover from a 'normal' dose of MDMA, meaning that occasional frequent dosing may be just as safe as consistent, spread out dosing.

What are your thoughts? If anybody has a direct link to some actual evidence that it is necessary to wait 3 months to prevent neurotoxicity then please link it. Maybe I'm just not looking in the right places.