My work has a shitty rule about vacation leaves. First, there is only 2 days allotment of leave per week for the whole team, meaning if someone got these 2 days, you can no longer apply for leave, also not possible to have leave for more than that. Second, you would only know if its approved one week before, even if you gave them few months notice.
Managers can use their time off for a week, no problem.
I had a trip planned with my partner for a week (we arranged it long back) and was planning to take sick leave because of this rule. My doctor can issue a medical certificate for me.
Sometimes I feel guilty that Im doing it but then it leaves me no choice but to use my sick days.