Solo Battles

If there is another thread on this I apologize, as I could not find a search engine besides one that searches for players.  But, is there a reason to do solo battles on the hardest level anymore?  I have been doing all of them on the hardest level out of habit and didn't even think to question if it was necessary until last night.

I thought on the pass there were tasks that talked about winning solo battles on certain difficulties, so if u do the hardest level then u would be working on all the tasks at the same time

Ive been doing it on the 2nd hardest just with my team being not great but can still get easy points. 

There may be certain tasks for something you have to do but you still get rewards. I think theres a blog here that goes through it but I cant recall.

Once you do 10 on legendary you don't need to do anymore until a new comp pass comes out. Once you finish all the solo battles tasks in the comp pass you're basically getting just 1 CP for everyone you complete on any difficulty. If you finish the comp pass there's zero reward to doing anymore solo battles.