I do not think editing and changing something then saving extends the original 30 days. I could be wrong. Never trusted drafts, always something goes wrong the longer you have a draft. Pictures disappear too.
I always used the schedule listing to hold my listing i am working on. Just schedule the listing in progress 20 days in the future (max 21 days) and list. Then complete the listing as soon as you can. If you need more time reschedule later in the future. Scheduled listings are free for non-store and 10 cents for a store. But the fee is only charged if ebay starts the listing at the scheduled time. When ready to list, revise the listing and change start time to start immediately, no fee.
Just don’t forget you have scheduled listing because they will start and could be issues if sold and listing incomplete!
Using scheduled listing is an old trick from years ago and was the only way to hold listing when using ebay online Sell Your Item tool back then.
Another way with the New listing tool is to save a listing in progress as a template. It has a limit of 10 templates. A bit tricky to work with until you know how templates work. I have saved listing in progress this way too.
