Alexander R. I use this sparingly to be honest. I treat them as true components. I have had a consistent CTA button be a component for precisely the case you pointed out.
Typically its CTA sections, contact forms, contact sections (email, phone, address, etc). Anything that will live on multiple pages without a lot of variance between them. You can nest components as well.
Any time I am using the CMS though, I tend to stay away from components but again its all situational really. Not sure if this was helpful or not.