Top up pot to reach value

So, over here I was talking about liking the idea of a fall back pot - a virtual overdraft, if you will.

It made me think that a neat idea for adding money to pots would be to set a pot value (e.g. £250) and a trigger (e.g. pay day). Then on pay day however much money you need in your pot to make it £250 would come out.

Does that make sense? (I think I’ve made a bit of a meal about explaining it). Any other circumstances where this might be useful?