There are those who are paranoid and those who are expedient. If you're truly paranoid, you spin up the thing you want to run, measure what it does, and open the holes to allow it to do what it needs to. It's tedious and sometimes error-prone, but in some environments it is necessary.

In the vast majority of the world, you set permissions to what's reasonable and trust that most of the time things will work out pretty well and have a plan for if you need to fix things on the fly.

I personally am not terribly paranoid, but I've worked places where we had to be pretty paranoid (shared hosting).