Any regression type defects can be spotted early and with a minimal amount of testing as compared to running a single, long regression run at the end of the cycle.

By combining the two principles of targeted testing and cumulative results analysis, tests run early in the testing cycle may never need to be run again, with their results retained until the end.

If there is some uncertainty that can only be resolved by a very rapid cycle of edit-and-run, then TDD is likely to be more of a hindrance than a help.