Direct Debits - When?

Hi,
When do you take DDs? - monthly, quarterly or what?
Whatever, do you decide an average figure?
My preference is to pay via DD, but only for the actual energy I have used.
Thanks

@Sire There’s plenty of information about how a Bulb account works in Help. Here’s the payment page.
https://help.bulb.co.uk/hc/en-us/articles/115003405632-How-do-Bulb-payments-and-statements-work-