Some businesses open only at night, other just during day, while others 24hrs/day--ie hospital.
There is law/limit in term of #hours a teen
can work per wk, there is no real limit for adults. Before signing the contract to work, read the policy and make sure you understand it well. There are laws companies musy abide, and if u don't abide by your company, u may lose your job. So, ask your boss.