In fairness, those plastic bags they use these days make proper bagging very difficult. Paper bags were all I had to work with in the 1970s and I became very good at it. Cans on bottom, boxes along the sides that provide a space for more fragile items in the middle. Sometimes I'll get behind the register if the cashier is by herself and will amaze her by having everything bagged by the time she turns around. It's been over 40 years since I bagged groceries for a living but it's like riding a bicycle.
A really good checker/bagger combo will put all like items together as much as possible.
Bathroom items.....canned goods...frozen goods... fragile items...THOSE teams knew their job!!!!