I'm guessing the Base and Pro chips come off the same wafer, and they get 5 Base chips (some defects) for every one Pro chip (very few defects). So they run the Base-model assembly line for six months and eventually they accumulate enough Pro chips to satisfy Pro-model demand.

Pro chips come much later than base chips and vary significantly in ways other than number of cores (which can be up to double), such as doubled memory bandwidth and peripheral support (thunderbolt 5 instead of 4).

You mean as in binning? High defect rates for chips but they're burned to disable non-working parts and sell them as non-pro chips and accumulate the good ones ?

As others have said, the pro is a different mask set.

But you are right, they do bin. You can get versions of the cpu with different core counts for this reason.

I’m only seeing this with the pro and max though.

Curious, where's 5 come from? Is there a reason for the specific guess or is it just an example?

If you look at the platform name and the kernel code you'l realize that this is not even remotely true. The base M chips are T8xxx which are (more or less) just iPad chips. The pro/max/ultra are T6xxx and are their own new thing, starting with M1 pro which was T6000

https://en.wikipedia.org/wiki/Apple_silicon#Comparison_of_M-...