What would seem Over Training may mean different things to different people, with different goals in mind.
Might be that Under Recovery (less, or no, rest between workout days) can be more counter productive than over training. It's how the body adapts and how you let it adjust to any given training workload. Some top level Olympic lifters can train 2 to 3 times a day, with steady progress. Though their training sessions are brief and to the point. Same could be said about gymnast, in some cases. And check out these gymnast with superior tricep, bicep, delt and total upper body development to those of the average BB'er..
BB'ers can have some of the most illogical approaches to workout of just about anyone. The funny part is, quite a few work very well for them. It's the question of how each of us adapts to any training scheme, to what most would consider over training. What's one persons over training might be something that another person can make steady progress on. Just have to find out for yourself.
Good Luck.