[Question] What is the right ratio between mentorship and direct work for senior EAs?

There is a re-occurring theme in EA organizations that one major bottleneck is senior researchers’ time. They always face the trade-off between doing direct work or mentoring less senior people. I think this is a very important question and I’m very unsure what the right answer is.For the long-term growth of the community, it seems plausible that some senior people should primarily do mentoring. On the other hand, there are important questions that need to be addressed right now and the next pandemic or AI risk isn’t going to wait until the EA community gets bigger. Thus, my questions are
a) Has anyone ever thought about this question in detail?
b) What factors would such a decision depend on? Intuitively, the senior’s ability to mentor and the urgency of the problem play a role but there is surely more.
c) Are there options to combine mentorship and direct work, i.e. can senior people reliably outsource simple tasks to their mentees?