This approach to careers fails to take into account that we inherently change as people.

In periods of ones life other things matters - maybe it is taking an education, starting a family, etc.

Other periods work matter.

It should be entirely fine to switch it on and off and change tracks throughout life - and in my view it seems like it is!

To reach a peak it takes roughly 10 years, but these 10 years can be started at 40 when your kids does not wear diapers anymore.