I am usually doing so if the comment is the only one or it is a high quality contribution to my photos or stories, then for sure.
I sometimes comment to others but not waiting to upvote my posts, it is just a little present if they do.
If you are networking like spiders and put a lot of comments on steemit you can gain followers and upvotes as well. I will continue upvoting the valuable comments because I usually do not get much so I can afford 5 a day.