Slow motion pull-ups will help develop a stronger mind-muscle connection, and they'll put the working muscles under tension for a long time. They require precise muscular control and offer a way to progress without doing more reps or strapping on extra load, which becomes more and more awkward the stronger you get. As a bonus, the uniform tempo teaches you how to ration your force application throughout a set.
The idea is simple: Make your pull-ups look like they're being done in slow motion. Use a slow enough tempo so that you can't exceed 5 reps per set.
Try to make the tempo as uniform as possible for each rep of the set. For example, don't let your first pull-up take 10 seconds from top to bottom, your next pull-up take 6 seconds, and your third only take 2 seconds.