I believe a sales copy should be short and to the point. Don't sell to the customers, but make an ad advertise a service or a product. If the product or service is in demand, targetted audience will purchase.
Big companies adveritise to their customer if they don't like the product then they get a refund.
Do you think a short ad ( I hate to say sales copy) would do better than a long sales copy?
Secondly How Often Do You Go To A Sales Copy & It's Too Long And You Leave because it is just too long?