I’m thinking only for downrigger trolling with the casting reels mentioned in earlier posts.
If I’m casting, then I’m using spin rigs with 8#.
When I’m DR trolling, i do have the advantage of not needing dive strength, so I can run lighter lines to help the lures run more naturally,IF a lighter line does help them.
Most of the problem when running Mono from my perception is from the boat pull going down to a single pull point, instead of a curved mouth of a snap lock, which allows lateral movement.