Ask HN: How are P&IDs used after they're drawn?

I’m trying to learn about how P&IDs are used by process safety, ops, and maintenance personnel.

I’ve worked as a P&ID drafter mostly doing redline changes, but I’m trying to learn how these drawings are actually used more broadly.

In your experience:

What do you personally do with P&IDs?

Would really appreciate perspectives from O&G, chemicals, or industrial ops.