In my many years of having several stores. (I close 3 stores during the summer months and give them the summer off)
I've never used GTC...I like to make my decisions on my items every 30 days.
Plus, it will come back up in the search engines as a new item every 30 days when a seller reuploads the item.
Just my vote, but I don't want the default being GTC.
My Best to you,
Donna