I had never used GTC until last month, so everything about it is new to me. I would just like to share an experience here with other sellers who are also new to using GTC with the OOS feature.
I have quantity of 1 on all of my listings with the OOS feature activated. So, when the 1 sells, I make another to replace it. Yesterday, I had a new item that has not been listed before and thought it might be good to do a "sell similar" using a like item that has been sold and replaced several times. This is where I learned I need to be very careful because the quantity field is prefilled with the total number listed and sold for that item...not the quantity of 1 it originally started out with. So, I had changed the title and the photos and was ready to hit list item, when I noticed the quantity was 4 instead of 1.
Just something to be aware of if you are new to using GTC and the OOS feature.