Can I use apollo client's reactive variables without cache policy?

I'm using apollo client. And I'm wondering can I use apollo client's reactive variables without cache policy?

According to the documents

New in Apollo Client 3, reactive variables are a useful mechanism for storing local state outside of the Apollo Client cache. Because they're separate from the cache, reactive variables can store data of any type and structure, and you can interact with them anywhere in your application without using GraphQL syntax.

I think I can use reactive variables without a cache policy. But almost all of the examples using reactive variables with cache policy.

Can I use reactive variables without cache policy?