While this can be a minor issue on an individual level, off-the-clock litigation has become increasingly prominent in class-action lawsuits. Operators must be aware of this issue.
Most employees believe they are on-the-clock anytime they set foot on company property. Most operators do not have employees changing into uniforms on the premises, avoiding "donning and doffing" issues, where employees are paid for the time it takes to put on or take off required clothing.
Most off-the-clock issues come up at the end of a shift dealing with a tip pool or finishing up side work that was unable to be completed during the course of the normal shift.
There's no one set of rules that sets precedent for whether an employee is on the clock, off the clock, or entitled to back-pay. The main issue is whether someone is subject to control by their employer. If an employee is dealing with individual tips and voluntarily tipping out other employees, they are not subject to managerial control.
However, when there is a mandatory tip pool, the employee must do something to reconcile the tips for multiple employees. This implies control by the employer before the employee can complete his/her work and could be subject to a successful off-the-clock claim.