I wish people didn't call it a "high". A sense of well-being and a renewed connection to your body is not rolling on E, unless a poet rewrites it. It's a great feeling for a lot of people, and all this talk about getting high is going to make the moralists schedule the stuff.
You can still feel better dosing the day after a whopping dose, so it's not a total waste. But like everybody's said, tolerance is fast with this stuff. If you keep it at like 1800-2400mg/day, you can maintain that modest (but wonderful) sensation for a couple weeks before it fades. Even then you'll benefit from a week off.
ANd during those days off, I don't get any withdrawals from 2400/day, I just miss the stuff.