I have a different use-case for timefield that was perhaps not intended by the author but could prove useful:

I want to use it for "length of time" where it records not time of day but a simple H:M:S duration. Not duration like 'event lasts from 2PM to 2:30PM' but duration like 'ran the marathon in 2:20:34' or this song is '3:45' long.

This would allow views integration to sort/filter the duration fields for examples below:

List of songs, sorted with the shortest songs on top
List of times for runners, sorted with the best time on top

And so on with filters (if field_race_time > 4:00:00) etc etc.

I imagine this would just be a field stored in the database as number of seconds, then a few PHP formatter options.

If this is already done here or in some other module, please let me know!