I wonder if the workload was high in part because you gave such an insanely good deal?
It took me a while to get my contracting rate up to where it was high enough to support me, and to feel comfortable asking for what seemed like large numbers. But the quality of work has actually improved the more I ask.
Contracting rate should be more like 150%-200% of your salary rate, since 4-6 billable hours are about the most you can consistently get out of a 10 hour work day. And that doesn't include the weeks spent looking for work between contract jobs.