It's my impression that Doctors are generally very conservative about this, for 2 major reasons:

- they take the Hippocratic oath very seriously. It's a big part of the culture and indoctrination of medical students.

- they've seen enough examples of people dying from seemingly minor conditions and others of people recovering from seemingly irrecoverable situations to know that their predictive powers are quite fallible

So sure, I expect Doctors to cut corners and make mistakes, after all, they are human. But this is one area where I expect that they're much more likely to err by not declaring death soon enough...