For obvious reasons that kind of time can never be used. It would mean that while in Ostende it is 4:00 PM, in Brussels it would be 4:07 PM and at the same time in Arlon it would be 4:12 PM give or take a few minutes. In our modern world this would be extremely confusing and totally unpractical which is why time is rounded up to the hour, everywhere.
Except... you're wrong. Countries do use offsets <1 hour, although 1/2 hour seems to be smallest common division.
(Iran, India, Myanmar, Canada, Australia are just some with 1/2 hour offsets. NZ and Australia have 1/4 hour offset regions)