I did the numbers with the AT&T sales rep here in South Texas, which has a similar plan and cap. If my math is anywhere close to correct (questionable), actually pulling 1000 Mbps would would exhaust the 1 TB cap in about 2.3 hours.

Yes, hours. That cap cannot sustain the advertised speed for even one full day before hitting overage charges.

Needless to say, we went with a different service provider. We are fortunate here to have an option (alas, still a cable company) that has no data cap, but not everyone is so lucky.

Yep, it doesn't take long.

https://www.wolframalpha.com/input/?i=1Terabyte+at+1+gigabit...

Think of all the "cloud" kind of things you could enable if you could use that bandwidth. Only we can't.

Think backups of your entire disk etc... massive p2p cluster filesystems stuff like that. All not possible cause of these data caps.