It's not even about grinding so much, I just don't see the purpose. I'm at 15 promotions total and while I can get killed very easily on the higher difficulties if I'm not careful - I can still hold my own on Perilous. I dont see the point of promoting and turning Perilous into Routine, lets flip the question round. Why do you feel that you have to promote?
Plz see my response above. I probably will stop promoting once I feel like my stats are getting too high. It's not like BW thought ahead to give me the option of limiting my benefits prestiging.
I'm more of a banner completionist. I figure the promotions will come once I've reached 37,500 runs. ( to complete all character banners)
I am very weak to peer pressure though, and since it turns out most of my DAMP friends list are leaderboard Illuminati, I cave to promotion.