What are the ideal thumbnail sizes in WP for responsive layout?

Question

Adaptive design

As you know, in WP you can set three image sizes, but there are many devices and resolutions. What are the optimal sizes so that, on average, for the hospital, the maximum number of users have to load less unnecessary traffic? Is there a middle ground? What permissions are you setting?

Answer 1

In WP , you can set as many image sizes as you like.
Optimal sizes depend on the layout.

Answer 2

The average size in my case is set to 0-0, I have not yet identified any cons.