"Inevitably, I would get burnt out and be wildly unproductive for weeks at a time."

I can attest to this and I think it is something that a lot of management types may not understand about the engineering work culture (at least in my experience). When we're in full steam our job's don't naturally lend themselves to down time like a game of golf with Gary from Sales might.

It's definitely a problem that I am still learning to deal with effectively and am always looking for tips/experiences from others.