When people get to the point where they can do a few reps of an exercise with okay form, there’s a tendency to abandon the less advanced training techniques. Once you can do push-ups from the feet, even if you can’t go all the way down, or the form’s a bit shaky – people give up on doing push-ups from the knees, thinking of them as cheating.
But there’s no such thing as cheating, really – you’re either doing the technique or you’re not, and there are various techniques at a range of difficulty levels, and if you need to be training anything, practicing techniques that help you to progress is always going to be best.
Consider starting with a set of jumping chins – set the bar a short distance above your head, but not too far away – grab the bar and jump from the ground until your chin goes as high as it can and come down as fast or slow as you feel – you’re capitalising on momentum, reducing the intensity – it’s not cheating, it’s a technique for training and progression, but it would be inaccurate to do a set of six jumping chins and then say you can do six chin-ups. But who cares? That’s just status-stuff, and has little to do with actual progression. If you can start to care less about the numbers you can get done, it frees you to train easier or more challenging techniques without feeling like a failure or that you need to qualify. You can also train partial range of motion reps, they can be useful – but the tendency is just to do more and more partials with a reducing range of motion because it feels like progress. What’s best is to use a variety of techniques with varying levels of difficulty. There will come a time when you have to increase the difficulty of a full range of motion chin-up – you’ll get there as long as you’re training with an open mind and thinking about appropriate techniques and progression. People often plateau when they can do a couple, because they get caught up in only training partial-chins.
What gets really hard is actually knowing how many reps you are doing, with accuracy, and being able to judge if you are progressing or not. If you can do more reps, but your range of motion is shrinking each time - is that actual progress? Are you getting stronger? Try finding ways to ensure that your range of motion is consistent - touch your toes to the ground each time, become really aware of extension through the shoulders, scapular joint and elbows, shoot for consistency and be honest with yourself, or something like that. Then, if the numbers are going up, you know you are developing - and if they aren’t, you aren’t fooling yourself either. You can go back to critiquing your programming, recovery, and things.
Once you stop identifying with the number of reps you can do, once you stop putting your pride on the line, it frees you to train in more diverse and challenging ways, because you're not hell-bent on getting ten reps out every time (damn the form to hell), because you're a real man, damnit! I can do fifty reps! I'm better than you! Blah-blah-blah. It’s a strange paradox or something - you can use the maximum number of reps you can do to measure your progress, but testing is different from training - so while you’re measuring your progress, you don’t want to get too attached to the numbers - it can be useful to train more challenging techniques for fewer reps, just as it can be useful to train easier techniques for greater reps, and if you want to develop your chin-upping ability, you don’t always need to be pumping out chin-ups. Variety will help too.
After the horizontal pull-ups, try some more jumping chins or a chin-hold where you’re just holding the top position of the chin-up for a period of time (think about pulling your elbows down towards your butt and squeezing your arms in towards your ribs, rather than lifting the chin), then maybe a set of pullovers, some towel-kettlebelll curls and a farmer’s walk. That’ll give you half a dozen or so techniques you can train, that are all geared around progressing your chin-ups, there’s a lot of repetition – which is to say, practice – and it’ll help you to progress more than just grinding out three or four total chin-ups for the day.
And of course, you can mix in any other strength training you want. Maybe you’re splitting your workouts into upper body and lower body days, or pushing days and pulling days, or whatever – you might do some legs training as well, or push-ups – that’s all up to you. Pay attention to what’s helpful – what’s useful, what helps you to feel good and satisfied on the day, and what helps you to progress over time.