knuckle conditioning will almost 100% lead to bad arthritis. I train at one of the top mma schools in the world with some of the top MMA athletes on the planet. We don;t condition our knuckles. There really is no need to do it at all. No added benefit. I’m sure my knuckles have become slightly conditioned from hitting the heavy bag and sparring, but even then i’m always wearing protection.
There is a reason you don’t see real fighters conditioning their shins or knuckles anymore. It doesn’t help all that much and leads to bad health problems.