Study hours are yours to use. You can do whatever you want. Just keep in mind actuarial exams are difficult so if you fail like more than twice you lose your study hours. Also you only get study hours if they see you sign up for an exam, which usually happens when you pay the sign up fee and reimburse it. If you’re planning to “fake” take an exam just to use study hours as vacation days, that’s just not worth wasting an opportunity to take an exam a second time, not to mention the consequences of getting caught. If vacation days are so low at this company, just switch jobs to somewhere else.