It could be within 30 minutes of correct for nearly everyone, if we decide that's a goal for the system.
Your days will be longer than 24hrs from winter to summer solstice, and shorter from summer to winter.
You cannot have the same time system across an entire line if longitude.
Which sunrise do you pick? The equitorial one? 45 north? This may be more fraught than you were considering.
I am far enough north that at some point as summer rolls around, I transition to sunset based structure, setting my morning alarm for 9 or 10 hours after sunset.
We could move from measuring time with a 24 hour clock to one based on solar angle.
We could also measure geographic distance in relative change of solar angle, combining our time and distance systems.
Some think it overly complex, but the increased geometry proficiency would save many lives.