I worked at a large web development company. The one thing which continually hamstrung the company was we had several large customers who were paying us a good chunk of money to maintain their web properties. They sucked up so much of our resources to keep them happy that other smaller customers suffered as a result.

The amount of churn we had was always the smaller clients who were still paying good money but felt neglected and would be open to changing vendors.

We went out of our way to mind the big clients and thought if we lost these few big clients it would so dramatically adverse the companies bottom line, we couldn't afford to lose them. This resulted in a situation where they were able to hold our company hostage, make unreasonable demands on time and energy and hamstrung our ability to keep our more loyal clients (who only bothered us on occasion) happy.

It was a good lesson there is a danger when you have a small company servicing a much larger company that you get into a position where your fear of losing them is a detriment to your other, more faithful clients.