It’s possible to make fewer requests without negatively impacting the user experience. For example, batching requests would result in a more responsive app.
He could just request 100 posts first, halving the API requests, but the app would be less responsive.
Your comments seem to have a confidence level that their content doesn't justify.
That’s too late to be sending the request if you want the premium feeling of no loading times while scrolling, especially if you also want to do rich thumbnails of media.