The most entertainment I get out of roulettes is queueing as a mentor. Otherwise, it's rare for it to be any challenge at all.
I typically only do them if I need something from them such as the EXP or tomes and queue according to my needs. If I'm bored, I might queue into Trials/NRs as a healer in hopes I get a spicy Arcadion run or Shinryu with a bunch of sprouts.
It's also a nice filler activity to do while hanging out with friends, but other than that I have tons of other things to do in-game so I won't do them for no reason unless I'm seriously bored and too tired for anything else.