Have you ever been in a car with someone who is learning to drive a car with a manual transmission? For those of us who have, I'm sure you can cringe at the thought of your body being thrusted forward into your seatbelt and back into your seat.
Well, working with businesses can be the same way. You run full speed ahead to get a proposal to a client, then they sit on it for a year. Then they call you up wanting to move on that project and need updated pricing. Again, you tell them that the offer is good for 30 days. On the 45th day they give you the green light, on the condition that it can be done in half the time quoted.
On the converse, you may work with vendors or employees that are waiting for your response. When you finally get around to answering, you essentially just took them from their seatbelt to the back of their chair. All in about the time it took them to figure out which question they had asked you weeks ago that you just provided the answer to.
Here's an article I found about trying to maintain a good tempo in business while trying to avoid the driving school scenario.