I dropped a trip because I enjoy drinking beer, going to the beach and shooting fireworks every 4th of July. The trip I dropped was a 24 hour trip and I didn't want to work over the 4th of July. There are plenty of trips on open time in July that I can pick up that are not over the 4th of July.
The question is: Does the company care? What if I dropped another trip and only worked 22 hours in July?
I understand that I only get paid for what I work, but my understanding is that the company wants you to work a minimum number of hours. I don't know what that number is, but I think it is around 50.