How useful, and how common, would a PhD in life sciences (biology/biochemistry/genetics/etc.) to become a patent agent? I anecdotally heard and read of a few people who struggled to find industry work with that degree, and were then recommended to try and become patent agents/attorneys as the PhD should allegedly give them an advantage in work applications.

From what I observed back when I was working at IP-specialty firms, it's pretty common and a credential that would be sought after. I think in the life sciences area, if you wanted to get into patent agent work and didn't have a PhD it might be difficult to get a position. By contrast, in other technical fields having a PhD is relatively uncommon among patent agents. I don't know to what degree my highly negative view of patent prosecution work carries over to the life sciences area, although I believe the "two class system" exists there as well.

Know someone with PhD in chemistry that went into to law, then onto patent law. It seemed a long road. Then it took awhile to become accepted. However, here we are 15-20 years later, and they work as much as want to work. Interesting, is that they are registered (holds bar?) In a few States and countries.

Could you elaborate on the much higher productivity expectations? Also, which part of it was high intensity?