The weighted pullup can be a hard exercise to progress in. If you can do 12 pullups you should be adding weight to your pullups.
The problem is though you can’t just add 5lbs every week like you can with squats or deadlifts. To progress with weighted pullups you need to work within a set and rep range and reach the top end of the set and rep range before adding weight. A set rep range I like to use is 3-5×3-5. Start with a weight you can do 5 reps with and do 3×3 the next session do 4×3 and the next session do 5×3 then reduce the sets to 3 and add a rep and repeat the process until you reach 5×5. This is a slow and methodical way of increasing the weight but it will work for a long time.
