[michaelt]

If your requirements are “must have accurate time, must start with an inaccurate time, must not step time during operation, no atomic clocks, must not require a network connection, or a WWVB signal, must work without a GPS signal” then yes, you need to relax your requirements.

But it doesn’t have to be the first requirement you relax.

[a_t48]

If it has a GPS already, it’s really easy to fall into the trap of just using it, but point taken. Then main requirement is accurate moment to moment time. Using GPS as the master clock mostly makes sense there.