Try this experiment:
Do as many pushups as you can on a day when you are rested up. Act as if someone is betting money on each pushup.
Do this every day.
See how long it takes before you are actually doing less, than more.
When you want to try and increase your best pushup count, see how many days of rest it takes before you can do that on a consistent basis.
To be fair, you have to basically do everything else in your day the same way. You cant do them one day after you've done a line of meth, and then three days later when you are so tired you can't read this post.
What is "over-training?" Is it the CNS getting overloaded too consistently? Is it the muscles being broken down and never having a chance to recover? Can you actually train your body effectively when your CNS is completely exhausted (regardless of the cause?)
CNS = Central Nervous System
I don't believe that our bodies will function well in ANY capacity when the CNS is exhausted. This is where CFS (Chronic Fatigue Syndrome) start rearing its ugly head.
Who knows? Could be all bullshit and just in your head.