Idea: Colleague Hours sacrifice

I was always a bit jealous by my friend who worked in phoneline customer service and could have a 'duvet day' if she gave enough notice (an unpaid day off or shift swap).

With all this technology emerging now, would you support Tesco allowing colleagues to 'donating' their hours to the Tesco app so another colleague could pick them up?

e.g. you want to go out Saturday night and prepared to drop either overtime shift or contracted time and someone else with the same skill is willing to pick up the hours and claims them on the app? Also, what's the maximum notice that would make this workable, do you think?