I haven't been a mentor for very long, but it's something I'm glad you're considering first, rather than jumping right in.
I think anyone CAN be a mentor and do a mediocre job which doesn't require much effort. Doing a good job, connecting with your students, and finding ways to help your students learn and progress does take more work. What you put into it, is what your students are going to take from it.
The whole point is to help newer members understand what's needed for the most useful reviews, and to help those who've been doing it for a while, to brush up on their skills. If you're not taking all things into consideration and you're just editing the reviews for your students, they aren't going to learn anything and will go on with writing reviews that could easily be improved.
Everyone teaches differently, but we all have the choice as to how much effort we want to put into teaching others. Putting in the effort and seeing your students go on to write awesome reviews without your help, is extremely rewarding! It's WORTH the effort!
I love being able to help others to do their best. I want to see everyone here doing a great job and if I'm able to help in some way, that's what I want to do! I truly don't believe that the program is for everyone and if you're not able to or aren't willing to put the effort into your students, than it's not a wise choice. If you want to do it, don't do it for points, do it because you have a desire to help!