That logically MAKES NO SENSE.
All characters improve therefore they improve at the same rate?
You need a course in how to avoid fallacious arguments.
Oh, and I'll give you one example.
Sengoku. No manga improvement. NONE. He was the same v Momo and v Kamio. (I heard he got stuff in the anime, but not in manga cannon)
And we know he beat Richard but even in that victory due to how little was shown we still saw no direct improvement.
But more importantly there are MANY other examples of important and popular characters SOARING in improvements compared to the peripheral guys.
Do you honestly believe that the saint Rudolph pair improved at the same rate as the Golden Pair? Or that Shinji improved at the same rate as Echizen?
The better people improve faster. And more importantly in drama the main characters improve faster.
It makes perfect sense. Echizen is the only character who improved on his own level. I said "All characters improve at the same rate because all characters improve after EVERY MATCH.
Sengoku is an exception, because he was too minor a character in PoT1.
To make it as simple as possible, I'll explain.
Season 1:
Kaidoh's powerlevel is 4
Fuji's powerlevel is 8
Tezuka's powerlevel is 10
Kirihara's powerlevel is 9
Sanada's powerlevel is 11
If every character improves at the same rate with every game played, and each character plays 1 more match, doubling in skill after every match, the end result will end up no different than the first statistics. The difference is every character will be stronger.
Season 2:
Kaidoh's powerlevel is 8
Fuji's powerlevel is 16
Tezuka's powerlevel is 20
Kirihara's powerlevel is 18
Sanada's powerlevel is 22