If you charge a reasonable rate, not really, unless you always ask for payment before you complete work. Let's say you charge 100$/hr. That means you are going to demand payment before you complete a full week of work. Say you charge $50/hr. Now you are demanding payment (in hand/check cashed) before two full weeks of work. Good luck finding a company/client who will pay you on that schedule.
Yeah, most of my consulting is really low-quantity in the hours arena, as it's not my main income stream. Anything more than a week f/t I'm really careful with.
I meant more viable from a legal standpoint I think.