The TV show details method has two fairly new fields, last_episode_to_air and next_episode_to_air which might be helpful for you to track what's coming next. If either of those 2 fields don't work for you, the only way would be to check the season like you are already doing.

There is no way to get a list of episodes that have been added per day.

Thanks. Is there a limit on the number of requests per day ?

There's no limit per day per-say, our rate limiting is enforced in 10 second buckets per IP address. You can read more about that here: https://developers.themoviedb.org/3/getting-started/request-rate-limiting

Thanks.

"You can use the X-RateLimit headers that get returned with every request to keep track of your current limits. If you exceed the limit, you will receive a 429 HTTP status with a Retry-After header"

That I add to this code (like X-RateLimit) so as not to get caught by the constraint:

<?php

$curl = curl_init();

curl_setopt_array($curl, array(
  CURLOPT_URL => "https://api.themoviedb.org/3/tv/xxx/season/xxx?language=en-US&api_key=xxx",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "GET",
  CURLOPT_POSTFIELDS => "{}",
));

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}