Model files in CI4

Hi,
I've started to develope my second project with Ci3, but now, after an upgrade to php 7.4, I got some errors, and I decided to rewrite everything in Ci4.
It's a big job, but the Ci4 Application Structure looks much more similar with the "right" MVC schema: I like it.
But there is something not clear to me in the documentation:
in the esample there is 1 model file, with 1 class, linking 1 DB table.
In my project there are more than 50 tables: must I make 1 model file per each table, or can I groupe all the [entity] classes (1 per table) in 2-3 files?
Where must I write the names of these files, in order to let them work?