I find that the opposite problem is more common - the 30 minute rule of thumb, to me, is to make sure that people don't spend more time stuck than that.

In a lot of domains of life, people expect you to know the answers, and become peeved when you don't. Much of software engineering is research, where asking the right questions is the job itself.

I tell people I'm mentoring that the maximum time they are "allowed" to spend stuck is 2 hours. (Nobody is policing that, just for emphasis). Ask as soon as you feel like it, but if you haven't made progress in 2 hours, you gotta reach out or else it starts to spiral.

I think it takes courage and humility to ask questions, qualities in the world that are often in short supply. The more we can provide positive feedback for embodying those values, the more we can all live up to them.