One facility I worked for 20 years, can't recall how many weeks of vacation were allotted when I hired on, but by the time I "retired" from there, after 21 years, I had 8 weeks paid vacation accruing per year. Holidays and Sick Leave were separate. I was often on call, and any OT worked, I could choose to put that time into the PL or Comp Time bank, to draw on later. Had very fair manager and department heads.
Current facility started with 5 weeks vacation, and that doesn't change with seniority. Holidays and Sick Leave are separate. I can accrue Comp Time, however, and if I need to stay late to finish something (with the boss's permission), I can apply that time to Comp Time Accrual. It will slowly add up. Have very fair manager and department head.
Another facility in the area: employee accrues SL and PL with each paycheck. Holidays come out of the PL bank. If you call in sick, the first 48 hours come out of your PL, and only if you are sick for three days, does SL bank contribute to your paycheck. Archaic and cruel, if you ask me. Benefits the employer, not the employee at all.
That said, it is not totally the amount of time one is able to take off, but if your department can tolerate having one employee gone for an extended vacation, without being a detriment to the work load of the department (and one's fellow employees who take up the slack). It's a two-way street, too, in that I have covered other employees more times than I can recall, -- we all worked short -- knowing that when I'm off, others will work short at times, as well. Hopefully it's a team thing, and we all give and take. And having a fair manager is a BIG plus. Ours understands we need to plan for flights or reservations, and doesn't keep us hanging, waiting for vacation approval. It's always best to get requests in as soon as possible, so manager can plan.