Steel is strong in tension but can be weak in compression if the profile is not optimised.
Profiled metal cladding acts as a beam, which derives its strength from the ability of its flanges, separated by the web to resist tensile and compressive forces. This strength can only be maintained while those parts in compression are restrained from buckling.
The geometry of the profile shape, together with the material thickness and strength, determines the load capacity of the profile. Manufacturing variations of profile shape from that tested will produce different results under load in pierced fastened profiles, and may produce vastly different results in clip fixed profiles.
Profile strength can be determined by analysis of sectional properties, but this will not accurately predict their performance under load, as the profile shape, and therefore the sectional properties, change during deflection. Only physical testing can prove the actual capabilities of the profile.