Dear native English speakers and English teachers

Please, can you help me with the following:

We seldom use short forms after names and nouns. Peter has got a book. = Peter's got a book. The children have visited London. = The children've visited ...

So do you use such structures or not???
e.g. Peter'll go to the cinema, I think.
Our teachers've told us not to cheat.

Is it not more common to use short forms after pronouns only??

Thank you KP