The hidden downside to a nice and organized project chat is that it looks trustworthy long after the context it needs has stopped being trustworthy. A messy thread is obviously messy, but a tidy one with an obsolete requirement hidden up front can give you the wrong answer without much cause for suspicion.
I would split conversations based on the cost of incorrect carryover. If I’m requesting wording changes, brainstorming, or other questions of the same material, preserving the existing chat is time saving or at least helpful. If I’m troubleshooting after the software was changed, a file replaced, or an approach rejected, I’d make a new chat to start fresh. It’s cheaper to repeat a few facts than to figure out which detail the Flipped Chat AI secretly relied on.
That makes it less about asking questions in ‘the same’ or ‘different’ projects, and more about whether the old context has any evidential value. Two questions can both be part of the same project, but need entirely separate histories to be asked accurately. At the same time, a chain of unrelated little questions could be kept in a disposable chat if none of the answers relied on the previous messages.
I’m a little less confident than @epicthinker4812 about instructions like “ignore all previous fixes.” That may work, but the discarded fixes are still sitting in the conversation. A better quick check is to ask, “Before answering, list the assumptions you are using.” If the response includes expired requirements or an abandoned fix, moving to a clean chat is the obvious choice. This catches contamination before you spend another ten messages correcting it.
I would maintain important information about the conversation outside the conversation, but not in the form of a complete transcript or detailed project log. A brief block containing the current environment, proved decisions, constraints and unresolved issue is sufficient, which is then used as the basis of each subsequent chat. The conversation can be modified or abandoned without having to argue over which thread contains the latest truth.
So my practical comparison is that continuing the conversation is faster at first, and restarting is often faster overall. I would continue when the previous reasoning is useful, and restart when it’s only the current facts that matter, and treat chat titles as a way of navigating the conversation, rather than proving that their contents are still current.