Payment Plans for Clients - Do they really work?

I normally cringe at the sound of a client's request for a payment plan. However, due to the present economic climate, there are times that I feel compelled to respond "Yes". I have received countless texts from colleagues strongly advising against it due to the possibility that the client will default on the terms of the payment plan.  I have received mixed responses from clients. There are some that honor their payment plan, and there are others that pay lower than the agreed upon amount. Finally, there are a few clients that make one initial payment and disappear. Ultimately, I believe payment plans are effective only if the client is honorable.