They might consider them dynamic but in 18 years the only time they ever changed was when I actually switched providers. They were essentially static IP addresses. With one ISP it was the same for 5-6 years.

Depends on your ISP, no? I've been in a few and for most of them I would have a different IP just by rebooting my router.

Im sure it will vary depending on the ISP, but I've just had a different experience. I put a dns record on a domain I had so I could ssh in because the IP never changed for years. But every ISP after dialup has never changed my address after installing. That includes att, charter, Comcast, Comcast again, att and att again, and some regional ISP I can't even remember the name of.