I particularly agree with the second point. Having enough hours is absolutely necessary to grow into a pro. And the number of hours spent is a non linear function, in two perspectives, from my observation:

First, spending 10 1-hour session produces way less pro-ness than spending 1 10-hour session. Every programmer who attempts a difficult (pro) project can probably attest to this.

Second, not all X hours/days produce the same pro-ness. People have plateaus that seem to stuck somewhere. But you need those plateau X hours/days too. I have a theory that one can avoid as much plateau as possible by always challenging oneself with an almost impossible -- yet still doable project. But it's difficult to get right, so a lot of people get a very long plateau, or burnout, and then quit.

PS: So eventually, anyone who is serious about a career must spend his hours efficiently on high quality (aligned to the career path, while challenging, but not impossible) projects.

PS2: The freedom to spend one's time is absolutely important. Marriage and children could bring havoc to this freedom so people should think carefully before treading into the water.