Basically it's an "oh no, anyways" thing. Makes programming easier since we won't be having them divert from the atomic clock. The largest effect is that in a century we might deviate a whole minute. Eventually, in a few thousand years it'll be a problem when it's off by an hour or so, but that's a future issue.

I was a house tech for fiber, but usually I'd ask the customer if they cared that I cut a coax so I could reuse the hole to go inside. Only once did they say no, as they wanted to use it to distribute signal through the house. That time was coincidentally the time I hit an electrical wire with my drill bit. Flames shooting out the wall are not very pleasant, even if it is just brief. Luckily the breaker tripped before a house fire started.