The article goes on to say:Ancient Romans didn’t measure time in our 60-minute hours; instead, they divided daylight and darkness into 12 increments each, a system they adopted from the Egyptians. In Rome, that meant an hour was about 45 minutes in winter and 75 in summer. Hours would have governed meetings, courts and dinners, but not in the carefully structured way so many of us experience today.
It goes on to describe how they were made portable, with dials set for half day increments (so you had to know if it was morning or afternoon) and lists of latitudes of popular places, which may not be the same latitudes we current use, and describes different styles of portable sundials. They weren't easy to use, requiring the user to know some basic celestial mechanics.But time was key to the Romans’ obsession with astrology, which made certain days or hours promising or foreboding for certain activities. Hundreds of funerary inscriptions marked the deceased’s time of or age at death to the hour. Time mattered, even if it wasn’t for trains or timesheets.
I knew just from surveying and navigation it was a lot easier to tell time from the stars than from the sun, but this really drove it home most times during the day had to have been "give or take 15 minutes" before reliable watches.