What is interesting about the concept of playing too rigidly as a mistake, is that one may not be able to prove it exists. If a player is committed to an attack killing a group, the game is likely to be won or lost according to the result of that fight. If the player blames reading rather than strategy, what can one say in reply?
There have been strong players (Kitani, Sakata, Fujisawa Hosai) with styles that are apparently rigid in their intentions; at the same time Go Seigen, Takagawa, Fujisawa Hideyuki were flexible. Perhaps it's not for us to judge. The difference between Kobayashi Koichi and Cho Chikun, otherwise having closely-related styles, may lie in Cho's policy of not being type-cast.