On my initial reading, I see no limit to the number of techniques a character can learn, beyond school restrictions and prereqs. For instance, a rank 1 bushi can learn all the rank 1 katas. Do I have that right? I'm just checking myself here. I have old edition preconceptions.

Yep! Can learn any number as long as you have the XP and pre-reqs.

Which is fine! I loved the idea of the lion kensai path in 4th.... but so many of the kata were pretty bad for their prerequisites. Now the idea of switching kata round to round is pretty good.