Is it normal for some VC backed deep tech startups to have non-full time founders? I will not promote

I recently got an introduction to a startup founding team of 2 in a deep tech space, and they a group of MDs and researchers. I believe they have raised a couple $$ from VCs, but they maintain that they are all full time. That being said, I have found that one of the cofounders still spends some of his time still employed part time in a clinic (2 days a week) It seems like the other co founders does a lot of daily running of the company. They seem content with that. From my general understanding it seems l