You should focus on the post, not on a user.
It is quite strange, however, that you are keep reading posts from some certain users (if you want some knowledge on some theme, search for this theme and not search a user, good at this theme). Maybe you have good purposes, but system can't identify if you are up voting a person to give him rep, or simply read all his answers for beginning to end and every answer is good.
The thing you are doing won't bring any rep to this user, all the serial votes will be reversed on the next day, but will bring bad outcome both to you and this user: he may be suspected having a sock puppet account and you can be suspended for voting serially.
If you like some answer, you can add a bounty on the post and award it to that answer, but remember that serially offering bounties can also be a bit strange behavior, you can also be suspected to be a sock puppet of this user.