If I spend the time researching and testing and writing an answer, I would like to know that I can publish it.
I have noticed that many times the Duplicate Post Police, (DPP), judge a question to be a duplicate without having read it, and often seem not to have read the allegedly "duplicated" question either.
Is there a better way to reserve a spot in the answers that publishing an incomplete answer and Updating it later?
Focusing specifically on your actual question:
Is there a better way to reserve a spot in the answers that publishing an incomplete answer and Updating it later?
No, there isn't. The way you attempted was to post saying "Working on an answer, will update this in a bit", which is posting a non-answer as an answer. That is already against the policy of "Only answers should be posted as answers".
There's no method to 'reserve' a spot in the answers. It's a "Post an answer before it's closed" race condition, there's no way to solve that.
The other proposed way you stated via a comment was to post an answer, then delete it, and later undelete it once it's actually an answer.
Thanks @ Thomas Ward: Is there a way to post, delete and resurrect an answer? If I spend the time researching and writing and testing an answer I would like to know that I can publish it
Nope, same race condition, and same problem as what you actuall yiddid - you post a non-answer, then delete it because you know it's not an answer, only to undelete later when it is an answer. This breaks the first rule since you're posting a non-answer as an answer. The only difference is you have the chance to undelete it after it is an answer, because it wasn't mod-deleted for not being an answer.
You still broke the "Don't post non-answers as answers" problem.
There is no solution to the problem of answering before a question gets closed as a duplicate or as unclear or {insert close reason here}.
There is also no way to reserve such a spot for your post - you either post your answer before it's closed and are lucky, or a post gets closed first. That race condition continues to exist, and though it's had proposals to fix it in the past they haven't gone anywhere.
Posting half-answers that are incomplete is also probably not the proper way to go about this, either, since incomplete answers that just say "I usually use {software} for this" would typically be a "comment, not an answer" such problem since you don't actually provide a complete answer.
Don't do that.
If the post is not a duplicate, and really deserves a unique answer, and trying to reopen it by voting to reopen, commenting, editing etc has failed, then solicit support in chat or post on meta to get it reopened. For me, someone wanting to post an answer is nearly always enough reason for me to vote to reopen.
Otherwise, post your answer on the target.
It's the fastest gun in the west problem. There's an MSO post about it where someone puts up a slapdash answer to be first, then goes back and edits it with details, so they're still first.
I'm not sure it's a solveable problem.
In the case of dupes, sometimes it makes sense to request a merge, which I have done in the past.
