In usual parlance, the limitations section is hard, other sections not quite so.
For instance, it is quite routine for airlines to seek an NTO (no technical objection) from the OEM for airline initiated variations to OEM published protocols. However, one would need to have one's ducks in a row to provide for a defence in court where one operates other than in accordance with the black and white of the AFM.
As, I think, we all appreciate, on occasion it is a matter that the end parameter was either a convenient termination chosen by the OEM or, for example in the case of cross wind testing, the best that they could find during the program.