GT- yes, you can overtrain while "on". In fact I did this at the beginning of my current cycle. It was the first few weeks, while the test was still kickin in. I felt the dbol so I figured I was good to go. Then on back night I totally bonked and felt like shit for a few days. Keep in mind that this was on a low volume/high intensity program too, so every set was to failure. I can still feel overtraining come on a little when diet/sleep aren't optimal. I simply take an extra day off or so till I feel better and start up where I left off.