In the case of Kuroko, the author had written himself into a wall, the tournament for the first couple of rounds had a one day break inbetween, and then from the quarters onwards it was one match everyday, so what growth all the characters had over the summer period plateaued with the first match with the generation of miracles, all the cards have already been dealt so to speak, with no gap inbetween to "refine" what they learnt.
This is how PoT benefited from the group match system, and it was used to great effect.
