It works for a lot of people who aren't great with money. If it's in their energy account they won't spend it on other stuff then be screwed in winter.
@Mablefly everyone's situation is different. There's no single 'good' amount & there are many ways of looking at it. I only over pay mine a little, just enough that when the statement comes out & it doesn't show the last payment I made they still owe me money.
my friend over pays hers a lot, because she can't budget in her head(or on paper) & she'll just spend it if it's in her account.
another friend has a separate account that she transfers money into, she keeps a note book with the updated total and a list of things it's for
2x rent
4x electric
3x gas
3x council tax
type thing.
she has another account with a separate list
6x weeks food shop at £80
4x weeks petrol at £60
4x weeks school lunches for both kids.
and she tries to balance it up so she knows she has x amount of weeks/months bills in case she loses her job etc
Friend A couldn't do that, she'd just see the money & spend it!!
Another friend tries to budget & be careful, then her wanker of a DH spends it all on nights out with the lads & then shouts when there's no food or bills aren't paid. He's an abusive bastard & I hope next time she leaves she doesn't go back!!
you just need to know what works for you!!