Should I test the whole return of a function or only a sample?

I want to test the return of a script that queries a list of urls (more than 1000), extracts some data from the response and returns it as an array of objects (dict) with certain attributes.
Is it safe to test only a sample from the returned list ?
My concern is mainly that exhaustive testing would be time consuming.

P.S. I am hoping that a random sampling would help catch errors, knowing that the response bodies of the urls my script queries may be inconsistant. Thanks,