Hi Vell, thanks for the question, it's one that has come up before, and doesn't have a 100% clear-cut answer. I'll steal your format for the answer.
The Short Version
The Long Version
We do encourage topics to be posted into existing threads where possible. When someone comes along well after the fact (E.G. you, now, 200+ days after the original) it's typically better to find one mega thread with all pertinent discussion than many scattered threads. Sometimes there can be many, many scattered threads, and a simple search then turns into a laborious task to research all available results.
However, if the contents of the new topic differ materially from the original, it does make sense to create a new thread. In that case, those who come after you may be looking for specific details about your variant on the topic. Or alternatively, they may not be seeking the variant you posted, but the original. In that case separation is better, as it allows searchers to find specifically what they were looking for, not a massive "glob" of somewhat unrelated answers.
That's probably not very helpful, but in a nutshell, we encourage posting onto an existing thread or into a new thread based on the relevance for future readers. The idea is to have all available info on a topic available in a single location, if possible. However if it is a new direction, or only slightly related, it probably should go into a new thread.
Hopefully that's enough guidance to get you started, and if you are unsure don't hesitate to ask for clarification (as you have already done).