That's not correct. The way you accumulate credits lets you run for a full hour ...

ColinCera on July 1, 2014 | parent | context | favorite | on: Low Cost EC2 Instances With Burstable Performance

That's not correct. The way you accumulate credits lets you run for a full hour at 100% CPU, once every 10 hours. So if you have a lightly loaded server most of the day, you can burst to 100% CPU for 2+ hours per day.