How do Cart hold times work?
You can let your shoppers "hold" their carts for a certain # of hours after they comment.
For example, you can give the 1st person that comments 4 hours to check out, During this time, if someone else comments to buy that item, they will get offered a spot on the if there was only 1 item in inventory.
Once the cart hold time expires for an item, it will be removed from the shopper's draft order. And if there was nothing else in the draft order, the entire draft order is deleted. If someone was on the waitlist, that person will get messaged that it's their turn to buy.
If you'd rather not have a cart hold time at all and have a "first-to-checkout-wins" system, simply turn OFF the Waitlist feature.