Does the "updated_at" field of a conversation gets updated whenever there is a new conversation part added to that conversation. I'd like to write a script which would query all conversations, check their "updated_at" fields and compare them to their previous values and if the values differ, the conclusion would be that a new conversation part was written for that conversation. Is this assumption valid? Then I would retrieve the parts only for the "updated" conversations.

Also a follow up to the question would be in relation to the hard limit set by retrieving conversation parts (500 max). How often is this limit reached? Is there a way to bypass this?