Sandwich Panels Screws Position

Hello,

for roofing sandwich panels (PIR CORE), contractor is proposing to fix the screws in the Through/Valley; but to the best of my knowledge; the roof piercing shall be at the crown/crest only to avoid leakage threats, I have searched a lot for a final proof to this but I couldn't find, also the manufacturer doesn't have any recommendations for this.
I hope you can provide me a final answer with a proof document for this issue.

Fixing the screws for what? The foam or the metal?

What type, brand, style metal roof is going over the top?

Thanks for attention,
It is roof sandwich panels Trapezoidal sheets of corrugated outer sheet 0.5MM GI (45/250), 100mm PIR core, and flat liner 0.5mm GI.
And I am asking for position of primary fixation of panels to the roof purlins (using self drilling screws)