From zgriner:

The idea is to let the MMF/bonds/CDs/T-notes provide the cash as they mature while the stock portfolio gyrates in the market. The assumption is the stock portfolio will provide a better long-term return than the bonds/CDs/T-notes, especially if left alone during down periods. This scheme forces you to use an asset allocation model with a yearly rebalancing to provide cash.

Zev

I quote above only part of an excellent post. Thanks, Zev. I very rarely print one, but this is a keeper. It's a mini textbook on managing the flow.

FoolishProf