Mentor Yourself First
In my old firm, we had a mentorship system whereby every individual was assigned a mentor at least one, if not two, levels up from their position. The role of the mentor was not just to provide day to day counsel but also to help guide the development of their mentees, and represent them during the performance appraisal process.
It was, overall, an excellent system but with one fundamental flaw. The success of the system depended heavily on the engagement and abilities of the mentor. If your mentor was naturally inclined, and interested in you, then you were in luck. If the mentor was respected by the hierarchy, then their advocacy of you would be better perceived (accepted) during the appraisal meetings.
Respected, engaged mentor = better positioning of you, and subsequently, your career.
Absenteeor under-performing mentor = not so good for you.
Yes, underlying systems were put in place to try and mitigate this but there's no denying the impact that the personal qualities of the mentor had on your trajectory.
Which is not to downplay the value of the mentoring system - I still believe that such a system makes excellent business sense and serves a valuable function within any organization. What it does show, though, and what I realized early on in my career, is that your career development has to depend on no one other than yourself.
So, to be clear, don't discount the value of your mentor. Absolutely seek out their counsel and guidance.
But don't stop there.
Manage your career actively and aggressively. Look for high performers across your organization and go learn from them, model them.
Look outside your organization at other institutions and see what makes high performers tick there.
Read voraciously on what drives success in your space and pick out the nuggets of wisdom that will bring value to you.
Don't accept the conventional wisdom of what drives success - do what is aligned with your organization's mission, your team's goals and your ultimate client. In other words, think for yourself.
And if your current mentor isn't cutting it, find a new one. (My very first mentor was a very good consultant, but he was completely un-involved. Mentoring didn't come naturally to him and he was never around. I knew that if I relied on him, I'd be in trouble (or at minimum, have a much harder road ahead). So, I engineered a change. I found someone who was involved, interested and - appropriately - asked to change mentors (or rather, I asked my new mentor to suggest the change). Everyone was happy and I actually believe that my original mentor was relieved to have one less mentee. Then again, it could, of course, have just been me!)
The bottom line is - take charge of your own career. Corporations put such systems in place with the best of intentions and when they work, they're excellent. But when they don't, the only person who gets screwed is you.
Unless you take charge.
Don't outsource the management of your career. Do it yourself.