Why is Google Page Speed ​​not satisfied with the caching time of third-party files?

Question

Client side optimization

When checking the site with the Google Page Speed ​​service, the service is dissatisfied with the caching time of third-party files. How to understand what caching time to set?

Answer 1

The caching time should be much longer, the examples in the articles say from 30 days to a year ( link1 , link2 )

Answer 2

because it's a robot, you don't have to trust it much, it only gives recommendations.
try to scan Yandex itself, you will see what errors it will show, and in Yandex specialists will be better than us)