Less Is More
"Rank doesn't mean anything of itself. What counts is what you know", somebody once said to me. Rank in the martial arts is generally equated with knowledge. What about applying what you know? With that said, is it advisable to acquire knowledge of a multitude of techniques or is it better and more practical to have just a few at your disposal?
In boxing, there are four basic techniques: jab, cross, hook and uppercut. Yet an endless array of combinations and tactics are at hand for the boxer's discretion. "Shadow boxing" is the pugilist's version of kata (practice forms). Most karate systems offer over a dozen of these forms to be learned through black belt and beyond. Choki Motobu, Okinawan karate's early embodiment of a tough guy, preferred training on only one kata - one that he felt utilized the necessary side-to-side movement for an actual street fight. Since Motobu's version of bunkai (application) made use of an unwitting but usually very willing uke it's hard to argue with his methods.
Learning a plethora of skills is one thing; knowing which ones to use in a moment's notice is quite another. Practitioners who fear arriving at a plateau in their art probably aren't being creative enough with what they already have or don't have somebody capable if showing them how. Variations are key, and it's quite often just a matter of focus. For example, the bunkai for an outside middle block as shown to a novice is strictly defensive - it's just a block. For a more advanced trainee, the very same block turns into a backfist driven into the biceps of the attacker causing muscular trauma. Defense becomes offense (kobo-ichi) all from the same move. Understanding the depth and variety from a select few techniques is far better than a cursory view of too many.