It is for most startups, but not megacorp which has the money anyway. I’ve never gotten close to hitting the CI minutes cap in companies < 100 engineers.
The cap is 2000, will 50 engineers for example really only need 40 minutes of build time each in an entire month? That’s like 5-10 builds, depending on your build duration.. just one or two a week or so. You might use all that up in a single pull request.
In a really productive month my two person startup had to buy more minutes.
I could have sworn it was more, but fair enough! I do heavily optimize CI to reduce minutes though, with easy access to local tests (and git hooks to enforce these) and more thorough tests ran nightly on merged branches.