Which sites are you using? TestMy.net is usually a good benchmark when your ISP is attempting to game things. Netflix’s fast.com is a good measure to see how well you can stream even if other traffic is throttled. Cloudflare’s test is a good measure of well you’ll be able to hit most of their infra. Many ISPs and majors (eg Google) just white label the Ookla speed test which is one I really don’t trust. On Spectrum I’d get an order of magnitude difference between Ookla and TestMy. However, collecting all of the tests will give you a good idea of the spread.