Basically every test has a time limit in school. No one save a small number of learning disabled kids struggles to finish in time. If it takes you the whole time you don't know it!
Taking longer can help your career, but there's a limit. Test times were always very generous for people ahead of the curve, short for people below, and just about right for everyone else, because that's how they're designed.
Ancedotal, but when i was in school i remember people top of the class were often last to finish their test (i guess because they double checked things more).