It is intuitive that there would be a limit on the skew angle of design strips. One reference guideline is the Eurocode (EC2: 4.3.1.1 P(8)): "For slabs, deviations between the direction of the principal stress and the main reinforcement of less than 15 degrees may be ignored".

This suggests that flat slabs / flat plates should be designed for two directions that are between 75 and 105 degrees apart, which means the skew angle should not exceed fifteen degrees.

The span segment property Skew Angle enables you to manipulate span segments such that design strip cross sections are normalized in each direction.