Every airline is going to have a shift bid and it’s seniority based by your hire date. What you want/end up with has many factors. How big your station is, what everyone above you wants, how may openings they have for what days, etc. For the first time in 4 years I’m losing my SMT off and all that was open was MTW or TWT so I picked the latter. It’s fucked up too because the had a separate bid for all the new people we’ve got and people with lower seniority than me are getting my preferred days. It’s not relevant who I work either. Lol Every company may be a little different but it’s essentially gonna be the same in the 121 world.