A senior reserve holder can get most if not all the days off they want. I’d say once hiring ramps up maybe after a year here and you’ll be able to hold whatever days off you want as a new hire on reserve (at a junior base). As a line holder I’d say you’ll start getting 80% the days off you want at about ~40% as a lineholder depending on what the people above you bid. Now if you want Friday-Sunday off that will obviously go more senior since those older folk tend to have a family and are likely going to bid that every time.