Smearing is not suitable for all applications, however. For example, anything requiring sub-microsecond precision (i.e. data acquisition) would require at leas

Smearing is not suitable for all applications, however. For example, anything requiring sub-microsecond precision (i.e. data acquisition) would require at least a 12-day smear to not fail its timing requirements. Such precison is well outside the realm of NTP but is not really a problem for PTP. I've worked on Linux systems that have done this; ~100ns synchronization was not uncommmon. (PTP, incidentally, got it right and specifies that its timescale is based on TAI, so it is continuous.)