Daniel, so over-training in it’s classic definition is a possible risk but in cycling for most riders does not seem to be such a problem. Maybe over-reaching and burnout can be. But the biggest problem is that because most people have a limited amount of time in order to maximize CTL they push towards more intensity. A focus on more intensity for 4/5 days a week has been proven a less effective training method.
That said, if we look at the chart provided by @aguti00 this is a text book perfect PMC chart. It’s valuable to see that the PMC chart looks reasonable and perfect is usually a safe bet for most people to ensure you are getting a good balance of stress and recovery.
So I would say rather than a CTL focus, having a TSB or ATL as a focus for one of the legs of your plan is good and by optimizing your TSB for example you will end up with a decent CTL ramp rate. So PMC metrics are valuable but more from a verification and risk aversion stand point and not from a trying to maximize your CTL stand point.
CTL has 3 components, consistency, duration and intensity. Intensity is the least valuable and most risky (to reduce your training effectiveness) portion of this metric. The problem is most people feel that intensity is the part of these three they have the most control of.