My view is this.
If the customer does end up paying within a week, it's of no benefit anyway going to DD as it takes just over a week from making the collection request to the money landing in your account. You may aswell just leave it and wait.
If they are more than two weeks late, and it starts to become a problem then going into DD is a good way of retaining customers, but they may be put off with the money coming out of their account 7 days after you cleaned them, especially if you (like most on here) text the night before to give notice of the clean and it may not be enough time to ensure finances are in order by the time the payment is processed, this is why they are reluctant to sign up imo.
One way to get around this.
1. Give them a next clean date and stick to it
2. Take all payments on a set day, i do mine on the 26th, and tell them that payments come out on that day, no matter when the clean takes place, this is by far the easiest for me and my customers as they know that on a set date the window cleaning money gets paid and i get all due accounts in before end of month, they can budget for it and it helps me retain problem customers.
Now if you still have customers who wont sign dd, and are pad payers, either dump them or have an effective credit control procedure in place.
For me, once the customer is overdue by more than 7 days, they get a daily reminder text.."Dear customer, please remember to settle your window cleaning bill as it is now overdue for payment best wishes Marc Stock StockClean" it doesent change evey day they get that until they make the payment. It works very very well.
Finally if you do have a customer who cannot pay, then a credit card machine is always an option.
I know in an ideal world, it would be great to have everyone sign up for dd, but in reality you loose a lot of customer contact and control when they use dd, as i feel that a small portion of customer relationship relys on the credit control aspect.