back on topic...
It depends on the discipline. Or really who's fighting who and to what degree. Some people prefer the "don't get hit" approach, and don't wear armor at all.
(A suggestion to all those "wailing on each other with sticks," Ten foot planks with a handle carved into them are indeed capable of beating someone with a katana. They are however, NOT very good for blocking said katana. Neither are your knucles. )