If you are organised and always remember when everything is due to be paid, dont mind doing online banking whilst on your 6 week adventure holiday etc then I'd agree with you.

Go over to any consumer rights type website however and you will see thousands of posts from people who don't pay by DD who either forgot to pay as they were on holiday at the time or their statement didnt arrive so they forgot/ didnt know the due date/ amount etc so they get hit by a late payment fee and/ or lose card perks like cashback or interest free period

DDs are very good for those of us that are occasionally forgetful or a little too "I'll do it tomorrow" or simply want the convenience of not having to remember/ not having to do banking whilst you on your extended holiday etc. It is important however that you remember how each of your DDs react to additional payments made before the DD is collected.