Spitzig and Richmond [1], investigated the effect of hydrostatic pressure on some Aluminium and Steel alloys and realized that the yield response was sensitive to hydrostatic pressure.

My question is that is this observation specific to the tested metals or all metals? If all metals are pressure-sensitive, why are still conventional yield functions (pressure-insensitive) so ubiquitous?

[1] Article The effect of pressure on the flow stress of metals