Major Programs such as Gnumeric provide an "elapsed time" time style: [h]:mm:ss which interprets the hours not as a time but as a time duration, so the presentation may look like: 34:12:00
(34 hours, 12 minutes and 0 seconds). SImilarly [mm]:ss would yield 194:12 (194 minutes and 12 hours). THis appears to be a heavily used format.
Currently this can't be achieved in ODF styles:
time-style does not appear to provide a way of specifying that the hours (or minutes) should consider the whole value.
number style cannot be used since one can only show a single number (and one can't calulate the seconds from within that style.