I hate

In my nearest Saino's Local I rarely buy more stuff than fits in a single bag. It's all about whether there is someone by the tills when I'm about to start scanning:

• If there is then I get them to do their magic to allow my bag to be used on the scales = no delay
  
• If not I just scan it all onto the packing area and then, when paying, pack it all into my bag with no interaction required.
  
  

There's also a way you can scan a bunch of items (5 or 6) onto the packing area and then move them all in one go to your bag which is on the floor. The scales think you've been packing into a bag and lifting it off when full.

In the bigger Saino's then scanning with the app and packing as you go is the answer. Very little nonsense and interaction required.