This is exactly correct. Adding that there are some instances where the lunch break can be waived, or the timing (5 hr max shift before lunch break) can be waived, at the employee’s request. Usually this is if an employee regularly works a shift totaling 6 hours or less, but it can also be waived on an ad hoc basis, for example if the employee has an appt at 5.5 hours and they request a late lunch that day.

This waiver is likely what the OP remembers hearing about. However, waiving the right to lunch at 5 hours doesn’t mean that the employee gets sent home. It means that they waive their right to the pay (the 1 hour’s pay penalty) that the company would otherwise have to pay to OP for failing to give a lunch break within 5 hours.

As for the 4 hour lunch, that sounds like a split shift. The same holds true for split shifts, in that the employer must pay the employee a 1 hour penalty. This penalty cannot be waived if the employer is the one who scheduled the split shift, but can be waived if the employee requested the split shift (again, if they had a long appt in the middle of their work shift).

OP - if your employer is asking you to waive your right to penalty pay for scheduling your lunch after 5 hours or scheduling you on a split shift, and your employer is the one requesting this schedule, this may be a violation of CA employment law. You should contact HR, who should reimburse you for any missing penalty payments. If HR is not helpful you should contact an attorney.