I think the default way to format a time should be HH:MM:SS.000
Currently the default time format is MM:SS.0 which I don't find helpful because I don't know which hour the time is from. Alternatively we should able to set a default time format for Excel
The default time format is taken from your system time format. In US English, it is h:mm:ss AM/PM
(actually it is [$-x-systime]h:mm:ss AM/PM)
Thanks for the quick response Dan!
To clarify, this is specifically for opening CSV files with fields formatted like 12:34:56.789
My Excel sets them to custom format mm:ss.0
Currently my system short time format is h:mm tt and long time format h:mm:ss tt. I verified that if I select time from the formatting dropdown the cell will reformat to h:mm:ss tt