This is a post that has been in my head for ages, but I want to write it in an objective way, not in a whiny way. And I think I'm ready for that now. I can basically summarize this post in one sentence: the time, energy and investment your academic mentor has for you is a large determinant for your career-success, but is extremely hard to predict when starting a project.
Let me explain myself more, starting with the first part of that sentence. Sure, there are different mentoring styles, but in the end it is important that your mentor has your best interest in mind. And I have found that this is not always the case, because a mentor is usually a busy person, and somebody with their own interests when it comes to project ownership, collaborations, etc. However, I have also seen mentor who - despite being extremely busy with things that matter to them - invest lots of time to get their trainees to write the best papers, come up with the best ideas, find their own niches and write the best possible grant applications. And from what I see around me, having a mentor like that can be just that extra important thing that you need to succeed in a highly competitive environment.
The next part of the sentence is the thing that you can influence yourself, which is to find exactly that mentor as a post-doc. But how do you do that? How do you know if a PI will be that mentor, and more importantly, whether they will be that mentor TO YOU? Because as much as people might not want to admit this, there has to be some sort of click/chemistry/connection/
And to end with: in this post I've used mentor and PI sort of interchangeably, but in real life a mentor can be a different person from your PI. It's nice if your PI is your mentor but if push comes to shove, you're responsible to look for people that can give input and challenge you to move forward in your career. This can - and perhaps should be - more than one person.