When is it Okay to Join a Conversation on Ham Radio?

When is it ok to join a conversation on ham radio?
Here are some opinions that I have copied and attributed to the author. What do you think?

Joining a Conversation in Process- (ARRL.org)

Remember that private conversations don’t exist in Amateur Radio. If you don’t want to call CQ to start a conversation, you can join a conversation that is already in progress. Listen carefully to the operators. Are they having an animated, involved discussion? If so, it may be a bit rude to interrupt unless you have something important to offer. If the chat seems casual, the operators may not mind someone else joining. So how do you politely interrupt? The best approach is to wait for one station to stop transmitting and then quickly announce your call sign:

“Yes, Charlie, I hope to get the dipole soldered together this weekend if the weather holds up.” “N1RL.” “Ah…we have a breaking station. N1RL, go ahead!”

Do not use the word “break.” You may hear other hams doing this, but you should only say “break” when you need to interrupt because of an emergency.

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