Hi,
Are the following sentences natural to a native ear?
1. He knows what it is to work with John.
2. What would be your best guess as to the size of those lots?
3. Has there been any update on the conference?
Thanks,
MG.
Yes
Thanks 5jj.
Not a teacher.
The first sentence seems a bit unnatural to me. Even though it is grammatical, I would not be likely to encounter it in my daily life. I would phrase it: "He knows what it is like to work with John."
Maybe it's a difference between AmE and BrE?
It is perhaps more common with 'like' in BrE, but it it is fine without.
Context is always important; labelling is rarely important.