Wall clock time should
never be used to measure time when these seconds matter. Like I said in grandparent comment:
> for time measurements you should always use a monotonic clock, not wall clock.
POSIX time isn't a time elapsed standard. Yes. But neither is iso8601, timestamp+timezone, everyday speak time "tomorrow at noon", or any of these other options.
So I'm not sure what your point is, other than to say that a hammer is not a screwdriver.