How do you handle it as a player though? Most of your responses in this discussion have been about how you view rules from the player perspective, so that’s what I was asking.
Do you feel it’s up to you to determine what your PC knows? Or the DM? Or some combo? What if you have different ideas on what would be common knowledge or knowledge available to a PC?
Can you elaborate? I’m not following this; are you speaking as a DM or player? It also seems to be about what you know; what about the character?
When do you deploy dice?
I ask the DM if I know unless it's been previously established that I should based on play history and background. Assuming that I personally know something or think my PC should know because of some background I've shared with the DM.
For example, pretty much everyone knows what trolls are in my campaign world. If I've never played with a DM I don't assume my PC knows. But they may or may not know anything about a random monster or bit of information that's not common. Who was the 4th ruler of the Kingdom of Whatzit? Maybe the PC happened to come across it in their studies, maybe not. If they established that they are of noble birth and are proud of the fact that they can trace their ancestry back to the founding kings and queens of the Kingdom of Whatzit then they know it. They can't just make up justification on the spot.