Not everything requires making a component. A CSS class can be fine, and I'd always use the least powerful way first. This is how the framework is meant to be used - that's the entire reason for having @apply.
https://tailwindcss.com/docs/extracting-components
I don't understand what you mean by ad hoc. It's a very structured approach. When utility classes don't work, you make a semantic class. If that doesn't work, you make a component. You can even use BEM naming if you want, you'll just be making a lot fewer classes.
Only if you are using a component framework or something that works like it though. Otherwise you should make semantic-style classes, yeah.
It‘s ad-hoc because you can not predict what a class contains (tailwind classes) or how it is spread through your codebase (BEM classes)