How to make get for drupal behaviors to run only once?
If your script is high-level, which is most likely, then only run it when the context is equal to the document.
I found this trick in the autologout module and use it almost everywhere now:
Drupal.behaviors.dosomething = {
  attach: function attach(context, settings) {
    if (context !== document) {
        return;
    }
    // Do stuff here but still use .once when attaching behaviors.
  ...