How to test the wiring duct fingers strength?

How to test the wiring duct fingers strength?

Normally, we bend the fingers from 0 angle to 90 angle, some times, the person test it from 0 to 270 angle, which one is suitable? If we put the wiring duct into the panle box, what angles we can bend it? I think it will be less than 180 angle,as there are some cables inside the trunking, and the trunking is also mixed in the panel box, it is impossible to bend the fingers more than 180 angle.