In my PhD, I've had two mentors with very different mentoring practices. First one was very hands on, tracking even what time you were in the lab, and the second rarely visited lab. I realized things didn't work out with the first, hence my switch to the second. I am now very happy with what I did. I now know that my productivity goes down with increased pressure.
So, there must be two ends of the mentoring scale. One extreme is very hands-off, to the point that your advisor doesn't even know your project and the other would be you are not allowed to leave the lab or do any experiment without your advisor's approval. And you punch cards for your time in the lab. In my experience all mentors can be measured in this scale. One smart lad can even come up with a formula or index at some point. It's too late for me to quantify mentorship as I'm on the other side of the table.
The choice is there for both the student and the advisor.
So, there must be two ends of the mentoring scale. One extreme is very hands-off, to the point that your advisor doesn't even know your project and the other would be you are not allowed to leave the lab or do any experiment without your advisor's approval. And you punch cards for your time in the lab. In my experience all mentors can be measured in this scale. One smart lad can even come up with a formula or index at some point. It's too late for me to quantify mentorship as I'm on the other side of the table.
The choice is there for both the student and the advisor.