When converting seconds to hours/minutes/seconds like this:
86399s converts to 23:59:59 but 86401s converts to 00:00:01 while I actually want 24:00:01
It's easy to calculate yourself but feels a bit cumbersome, especially if you could do this for several attributes at once with the DateTimeConverter.
An option (similar to Excel) where for example [%H]:%M:%S would give 24:00:01 would be useful sometimes.