Swap a shift with someone once and you’ll know exactly how good their word is.

A swapped shift is a contract with a real penalty. If they do not turn up, you are the one explaining it to a manager, which is exactly what makes it informative. People who take it seriously confirm the day, write it down and arrive early. People who do not will tell you afterwards that they forgot, as though that settles it.

Start with one swap rather than a run of them. Confirm it in writing, even a text, so there is no confusion about who agreed to what. And when somebody covers for you, be the version of it you would want: early, awake and not asking for anything.