Just wanted to add, for just over the first 2 years I trained, I trained heavy every single week. Aiming to get stronger every single week, this was when i was 16-18. After close to 2.5 years I started needing rest periods every 6 weeks or so. Why? I was strong enough and training hard enough to put too much stress on the CNS. Nothing to do with age I was still 18-19.
The first year you train you really aren't putting that much stress on the CNS because the level you are lifting at. The weights aren't that heavy and you can't put the same level of stress on the muscle because you don't have the experience to do so.
I've been training 20 years now, I can stress the muscle with average weights, I always go to failure. I don't need to go heavy, to be fair with average weights I do the movements slower to feel it more. I can feel everything. I recently tried doing one set heavy and the next light through all bodyparts and it worked great, but i'm not going to exactly grow anymore unless I start on the gear again, it's just to do something different.
As Ben Johnson's coach Charlie Francis said and did, if his athletes broke a new PB in say the 100m sprint, he had them take 10 days off (since that's how long the CNS needs to recover) because they had stressed their body to the point with that one effort that it needed that recovery. But if they were just a kid or just up and coming then there was no need for it, the effort wasn't going to be big enough to cause enough stress on the body. With bodybuilding you can do about 6 good weeks then you need 10 days off to recover the CNS.
