Why sometimes a website requires solving a CAPTCHA but sometimes not?

My current recaptcha implementation is that every time a user goes to my website, they need to solve a captcha that will send a token for the backend to verify, but is it necessary to do that every single time they visit my website? I saw a lot of websites only need to solve once when first time visiting.

The issue names no file, test, or entry point. Start by reviewing the component's reCAPTCHA usage documentation and how the backend verifies its token; define whether the project needs documentation clarifying token lifetime and repeat visits. Done would require a specific documentation change and a clear explanation of the expected integration behavior.

Written by the indexing model from the issue text.