Difficult to understand why JDWs would want to muscle in on the early morning trade of the downmarket ( no insults intended ) cafe. Often clustered around a bus/ train station these low comfort formica topped table and plastic chaired "caffs" are better positioned for the early morning trade. Whats more these places have a name for quick service .Sometimes being staffed by family members customers can be known by name and their catering needs known before the customer opens the door or his mouth to order.
I can appreciate Alesonly comments having been a shift worker all my life. It used to be that there were few shift workers in town centres, the natural place for a JDW, may be things have changed with the UK's industrial base having gone down the pan.