Folley is right, many drugs that cause the release of dopamine, serotonin and epinephrine will result in such a high release that trying to follow it up a day or two later with a different drug that causes the release of the same neurotransmitters will result in...well, nothing really happening. For example, a few years ago I took LSD one night, and the next day tried mushrooms. I felt almost nothing from the mushrooms. That night (this was back when I started taking drugs and I had no idea about how they worked) I took MDMA, and felt a liiittle bit high for about half an hour before it went away. Most recreational drugs work on the same neurotransmitters so I wouldn't bother ever taking MDMA the night after taking something else!