I hope to someday write a book about the stories I've heard from people who think they have employment claims. One of my favorites was the guy who wanted to wear roller skates to work as a disability accommodation. Probably the most common thing I hear is people who get fired without any prior write-ups who believe that their lack of prior notice or progressive discipline automatically gives them viable claims for wrongful termination. But that's not necessarily true.
While progressive discipline is often a best practice, it is not always appropriate. Circumstances may warrant firing employees immediately, such as when they engage in egregious misconduct. Nor is progressive discipline legally required. Being "at will," as most employees are, means that you can be fired at any time, with or without prior notice. From a legal perspective, progressive discipline is largely a risk-mitigating device. The more it looks like an employee had advance notice of performance problems, and a fair opportunity to fix them, the less the employee can argue that their termination was unlawful. Where there is little inherent legal risk in a firing, such as when the employee is not a member of any protected classes (vis-à-vis age, race, national origin, etc.), then progressive discipline is not needed. In any event, no at-will employees are legally entitled to prior warning before firing. Nor are they entitled to written explanations for terminations, another common misconception.