Sure you can divide whether your comment has some value or not.
For example yours had a value ;-)

I think what's ok is when you make a valuable comment on a post with 50-200 comments and upvote it for visibility.
I don't have a problem if people upvote their comments 1,2,3 a day, but then they should upvote other comments and post as well.
In addition self-voting on comments should not too frequently.

Thank you for your good comments under my posts!