Introducing reported speech- has said/ said

Please consider the following sentences:

Jane Smith has said her son cries when she comes back home.

Jane Smith said her son cries when she comes back home.

Dave Bloggs has told me what we can expect of the show.

Dave Bloggs told me what we can expect of the show.

Now I'm aware of backshift and that you don't have to do so if what has been said is still relevant or refers to a future event.

So does it matter if I use has said/said in each case? Is it just a matter of me deciding whether I want to distance the reader in each case, or is there a more concrete rule? Basically, is using has said/said an option and it's up to the writer which one they want to use?

Would be great if someone could clarify this.

Thanks

A lot depends on the specific context, but, roughly speaking, "has said" implies at some unspecified time in the past, while "said" refers to a specific occurrence. For instance:

I ran into Steve yesterday and he said that he just got back from vacation at Big Sur. But the odd thing is that, in earlier conversations, Steve has said that he hates the ocean and hates California.

(A little contrived, but it should give you the basic idea.)