Rolling silverware, marrying ketchup bottles, menu tests, and the like are the absolute bane of many servers' existence.  Most, including those in management, are sympathetic to the plight of the server when it comes to these tasks, but it's still work somebody has to do... and yes, you, the employee are probably that somebody.  Legally, the employer can ask you to come in early, stay late, and perform tasks outside your job description.
Under federal law there is no limit on the amount a person can work in a day or week, as long as you don't drive a truck and are older than 16. Some states have differing requirements (ex. Illinois requires one 24 hour rest day in a workweek), and some professions are more heavily regulated (ex. Oregon limits manufacturing workers to 13 hours/day). Nonetheless, the general rule is that an employee can work 24 hours a day/7 days a week as long as the employer is complying with the minimum wage and overtime laws.
As for pay, the Fair Labor Standards Act requires that an employer compensate an hourly employee for all time during which an employee is necessarily required to be on the employer's premises, on duty or at a prescribed work place. Your employer cannot make you come in early "off the clock" or stay late "off the clock" to do any task that is for the benefit of the employer. All of the tasks asked about, including training, menu tests, side-work, and cleaning all constitute compensable time and count toward your 40 hour work week. If you go over 40 hours, the employer is required to pay one and a half times the normal rate of pay.
On a practical level, both employers and employees should respect each other enough to be able to make this work.  For employers, simple steps like (1) setting up a mandatory training schedule that employees can sign up for or (2)  building prep time and menu education into the normal schedule are pretty simple ways to respect your employee's time and avoid the "surprise" of having to stay late or come in early. For employees, being on time and having a good team attitude certainly helps. If all else fails, challenge your coworker to a rolling silverware race - it adds entertainment and provides a forearm workout, win-win.
Jonathan
Jonathan Boulahanis is an attorney in the Chicago office of Clark Hill PLC and is a leader of the firm’s Food and Beverage team.  Since Jonathan can’t cook like his Italian mother and the fast food was going to his hips, he became a self-proclaimed foodie. As an attorney, he has made a commitment to serve the food and beverage industry, no pun intended, by representing restaurants, bars, individuals, and other food and beverage businesses with various legal issues as they arise. You can reach him by sending an email to submissions@shiftgig.com.    
LEGAL DISCLAIMER:
The responses provided in this blog are for informational purposes only and not for the purpose of providing legal advice. You should contact an attorney to obtain advice with respect to any particular issue or problem. Use of this blog does not create an attorney-client relationship between Jonathan Boulahanis or Clark Hill PLC and the user.