If the large stores go the same way as the small stores you will be doing many different roles in a day. This is the way things are going. Moving away from "that's not my job".
The thing is, IF it was implemented properly I can see the value in this... in utopia it makes sense. Really busy time on front end, staff come off filling to man a checkout for half an hour. Quieter evening, checkout staff go and de-card aisles and work capping shelves etc. Fred from Frozen has called in sick, well Bill from BWS can help out.
As long as everybody can ensure there's enough cover across the store so that things are done to an acceptable level and there's enough time to catch up later in the day.
BUT it just seems to be an excuse to cut hours back to the bare minimum and then some, so robbing Peter to pay Paul.
Result = people get fed up and leave, the staff who are putting the effort in stop caring because they're so exhausted every day, standards go down the toilet, then either A- they realise and increase the hours, B- they blame the staff and managers.