How has the court determined that appellant waived his right to a formal revocation hearing?

The record shows that appellant was well-versed in PRCS revocations and made a knowing, voluntary, and intelligent waiver of his right to a formal revocation hearing. (See e.g., People v. Mosby (2004) 33 Cal.4th 353, 365 [prior experience with criminal justice system supports conclusion that defendant knew and waived his rights]; People v. Vargas (1993) 13 Cal.App.4th 1653, 1660 [court considers relevant facts and circumstances, including the defendant's experience, conduct, and background].) Appellant had already served seven flash incarcerations and seven PRCS revocations (a total of 420 days in custody) for failure to obey all laws, drug use, failure to report to probation, failure to drug test, and changing residences without notifying probation.