Don't do it because there's no point to unless you need player's recommendation so you can be a mentor. Otherwise there's no point in doing this. I only have to spam it now for the relic grind but after that is done it will again be dead for me. It's painful, boring and don't want to bother with it.

As for mentor roulette, this is just a different name for "you are queuing for things that lack people" so you regularly get into random extremes that nobody wants to do and some people sit in queue for 2 hours. Yeah, it is used as a filler thing. This has nothing to do with mentors.