My take on training volume is basically summarized in this graph below.
We all have a genetic potential which decreases with age. To reach this requires training, diet, rest etc … everything … think olympic athlete level of detail.
If we start as untrained, but do 1hr a week, we’ll improve in fitness. The improvement is fast to start, and eventually levels off.
If we do 3hrs a week (and that’s not too much, so we’re not over training), we’d improve faster and eventually level off too, but at a higher level.
If we did the magic volume/intensity/diet/sleep etc, then we’d level off at our genetic (well, genetic + diet + sleep etc) potential.
So the question is, how do I know what volume/intensity to do? I’ve ridden for twenty years, and alternated between training and just riding. I’ve started TR now (last few years were just Zwift racing really), and am doing SweetSpotBase LowVolume. I’m not looking to hit my genetic potential, but want to pop up closer to it for my 2019 A-Race (likely Park City Point 2 Point).