Professional Tradesmen: For a Cedar Shake Roof, Should I Cover the Entire Roof With Impervious Ice and Water Shielding?

Speculative and custom home builder here. I asked Claude to summarize the Cedar Bureau's optimal assembly for a cedar shake roof, and I noticed it's different from how our subcontractor has built these roofs for us in the past.

Our roofer on a previous 13,000 sf house nailed the shingles directly onto a universal layer of impermeable I&W shield. Claude warned me that this would undermine the ventilation of the shingles, cutting their lifespan in half.

But I'm aware of the likely possibility that AI doesn't understand building science, so as a sanity check: can any tradesmen familiar with the best practices in cedar shake roofing confirm for me that it is in fact a bad idea to use I&W shielding EVERYWHERE, instead of only at critical zones (Eaves, valleys, etc.?)

Here's Claude's brief Optimal Assembly summary, in case anyone knows enough about this to fact check it.