I saw an interesting post on a Strength and Conditioning forum that read something like this: “I tried the front squat, and it’s really hard. I want my back squat numbers to go up, so I’m going to work my front squat more.”
To which some other wise soul replied. “If you want your back squat numbers to go up, back squat.” (Or words to that effect.)
I see something similar happen a lot in combat sports and self-defense. People get seduced into doing something because it’s cool, or difficult, or different, without ever stopping to consider if they really NEED to do such a thing.
Students who don't have the fundamentals of Muay Thai down try to "develop their Boxing." People who don't know how to deal with a single, unarmed assailant ask about dealing with multiple armed ones. BJJ white belts talk about studying Judo to "work on their throws", and so on. (I'm not talking about cross-training, or studying multiple things at once, which is a different activity).
Is there a time and place for this kind of training? Of course there is. At various points in my Boxing and Muay Thai studies, I shifted focus to lean more heavily on one than the other. I boxed before doing Muay Thai, so initially, I relied heavily on that skill-set. As I became more comfortable with Muay Thai, I moved away from Boxing, but returned to it a couple of times to shore up what I felt was a weakness in my sparring. At each point, however, I had a reasonably solid foundation in at least one of those skills. I wasn't starting from zero in both.
If you want to get good at something, attack the problem directly. Want to be a good boxer? Box. A good Nak Muay? Do Muay Thai. And so on. At some point, you might discover that you need some kind of supplementary training, but it probably won't be right away.