Using a Service to expose better getter methods for a Node instance
Having a service for frequently used things like this makes sense.

That said, your code can be simplified a lot.

$node-&gt;get('field_fully_booked')-&gt;value == 1;


Does exactly the same. If you want to check something, then do a hasField('field_fully_booked') to avoid an error if that field doesn't exist.

This relies on magic methods, see https://wizzlern.nl/drupal/drupal-8-entity-cheat-sheet

And yes, I did not use a type safe check on purpose. There are cases where type safety makes sense, but entity field values are not type safe, it actually makes your code more error-prone, for example if you'd change the value with API and did a = 1, then your method would return FALSE.