I prefer to work on a three year basis. I figure the price at this years numbers and add a percentage for inflation for the next year. Then I use the second years number for a three year span.
For example, job is worth $1,000 this year. I add 10%, bringing it to $1,100. I'll use that number for each year of the three year span.
Granted, if I burn, I burn for three years. But as long as I'm doing my part right I have lined up work for three years. I don't have to spend time bidding it again or have to worry about it being there "next year". If I can stagger them out I keep a contract base in effect and it helps to shield me from lowballers two years out of three. I can also plan equipment upgrades knowing how much I can count on for a couple years.