I don't think that self-regulation is a limited resource, for three reasons:
1. It can be developed and grown, so it must not be firmly limited.
2. Some instances of extreme self-regulation occur out of the blue- when a large assignment is completed overnight, when a gossip must keep a secret.
3. It is possible- not easy or common, but possible- to live a life well-governed by the self, with good habits and a schedule and proper priorities.