Excel does a lot of time calculations, treating the current time as a
distance from midnight.

However, if all you want to add are two (or more) time intervals, and come
up with the total time, it gets confused.

For example, if you are adding time taken to accomplish several tasks, the
individual times, such as 10 minutes, two-and-a-half hours, ... do not have
anything to do with midnight. And if you add several time segments, you
should see the entire amount, and not the remainder after 24 hour chunks are
subtracted.

This is not an esoteric requiement in calculations. However, I have had to
resort to acrobatics to be able to accomplish such calculations.