Well, the problem is that I'm not sure we could actually leverage that knowledge. In order to compare the t's, we have to find the t's, which is the hard part :( But it is true that if we had good ways to early-out on t values, then we could definitely save work by doing it the way your suggest, since it would potentially put the maximum t value for the start of the second loop closer to the start point.
It is definitely a good thought, though, regardless!
- Casey