But just to be clear, any games that I've played since then will not be included unless someone else has uploaded them, right?
No, your new games will not be scanned, untill someone else uploads the game IDs.
The only auto-scan feature which is enabled right now, is that I periodically rescan games, which were not at a finished shate, during the initial upload in order to get the final results.
It's going to be a continual process?
Sorry in advance, not sure, if I understood the question correctly. Currently I don't scan games, unless they are "demanded" by someone uploading the game IDs. While it is technically possible to scan them in advance (WZ has about 8-10k games daily), it seems like a waste of resources, unless there is a greater adoption of the site.
From my personal experience: for regular updates of my own games, I find the "bookmark" way (#3 in my instruction on the site) to upload game IDs quite convenient. It is not that flashy and interactive as devtools console options, but once it is set, it allows to update games in just a few clicks.
And, if I were to re-upload games again, there's a check for duplicates, right?
Yes, the games which have already been scanned are not scanned again. This optimizitation is one of the key reasons, why I opted to do a web service instead of an offline tool.