how many times can I use a specific keyword in whole of my news site [on hold]

My site is wordpress , I use Yoast plugin and my site is a news site. we have events that are acquire frequently everyday.

When I use a specific keyword, yoast says: “You’ve used this focus keyword 2 times before. It’s probably a good idea to read about why you should not use your focus keyword more than once.”

I can’t use synonym keyword the specific keyword are searched what I have to do with this warning?

If I have not use a good keyword base on this wrong keyword the whole of post goes wrong, title , first paragraph , image alt and …

I appreciate you if guide me

Thanks