I have done the LOA for a vacation, I needed 15 days, almost three weeks or 3 work weeks. It had to be done, since I was going with or without a job to comeback to. I explained that I had to take every single day off since it was common for some ETL's to see someone had days off and schedule them for a shift on a day they would normally not work just because to "keep them on their toes." And you can't tell my husband who gets 5 weeks of vacation a year he can't spend three weeks of it in one shot. HR ETL nodded and approved it.
Or another way to do it, is separate time off requests.
Then you fall back to "My time will fill the shifts, since that is what its supposed to do"