short term tolerace builds in a completely different way than with lsd. mdma releases stored serotonin into your synapses and this serotonin is then broken down. so if you're low on serotonin due to using mdma you will not get the full effect, regardless of the dose. of course this is heavily influenced by individual brain chemistry. some people can have a good roll two days in a row (not recommended at all), some just get just the side effects.
after about a week pretty much everyone should get full effects again, but there are other factors to consider if you want to minimise your risk for long term tolerance and unpleasant after effects, so the minimum recommended time to wait is somewhere around two months.