Durations aren't ints, so find or make a type suitable for storing them. For a similar issue (cache durations that were expressed as a mix of milliseconds, sec

Durations aren't ints, so find or make a type suitable for storing them. For a similar issue (cache durations that were expressed as a mix of milliseconds, seconds, and minutes) I now insist that the framework type `TimeSpan` is used instead for expressing these durations - as that's exactly what it was designed for.