I had a similar issue which I raised with Shopify support – we hope to sell one-off artists’ prints.
I was a bit confused as when testing, items seemed to ‘stay’ in my basket for days.
But, Shopify left this message:
I’m still trying to test it properly, but I think they are right.
I added an item to the basket on Computer A, then 10 minutes later I was able to add the same item to Computer B.
I then did a test checkout on Computer B, went back to Computer A and was told my basket was empty.
But it would be great if others could confirm that this works in reality. It would be a nightmare for us to end up with 2 orders for the same item OR items sitting in carts, unavailable to others.
Hope this is of use – but would also welcome your feedback if you’ve been testing.