COBRA can be effective (or is inherently) as of the term date so you have continuous coverage. That said, it’s expensive AF
(Source: was on COBRA for the past 18 months, was annoyed that it ran out. Equivalent plans on my ACA exchange cost significantly more.)
I suspect for the average American the math goes the other way.
Source: Tried COBRA many times in the past decade (lots of startups) and it was never worth it. I wish health insurance wasn't tied to employers at all.