Time is an interesting phenomenon. It dominates everything both in physical and cyber worlds. All living individual or objects are under influence of time: getting aged. All data traffic are regulated with time as base reference for synchronization and handshaking. Everyone has equal amount of time. Time cannot be borrowed nor saved for later use. Time is abstract that cannot be touched nor felt its existence.
That said, how do we deal with time? This is really use case based. In time-sensitive action, time is kept down to micro or nano second. Examples are stock trading transaction and racing.
In certain case, “coarse” time reference may be used like the illustration that hour indication is sufficient – morning, afternoon, evening or night time.
It all depends how time reference is deployed in the use case, and how time measurement is secure to maintain integrity. Inevitably, a comprehensive risk assessment (not just cyber but the business as a whole) is required to understanding risk (e.g. any client side to manipulate the transaction time?) to derive the optimal protection. Of course, we cannot eliminate every risk but accept risks to certain level as part of the running cost.