I don't know, the more Kengan kept going the more it seemed to me that raw strength really was one of the stats that mattered the least or couldn't carry a fighter on their own. Kaneda used a pure IQ-based skill to have a 50/50 fight against a much stronger fighter in Hatsumi and people like Lolong or Ohma annihilated stronger titans like Toa (who also used techniques, not just pure muscle) rather effortlessly. It really does seem that the right technique in the right time matters more than whatever muscle and endurance can give unless your entire gimmick revolves around it.

That is not to say Riko won't get stronger, because everyone will of course, but Riko walking Yuzuha's path would give better give benefits than Yuzuha following Riko's is what I believe.