As a newhire you'll be on reserve for a while (or not, if you're lucky.) Even off reserve, as a jr. lineholder you'll get 12 days off per month. On reserve, you'll often get 4 on / 3 off. It can be quite difficult to fit in more flying around your SKW schedule, and if you commute then it's nearly impossible.

Once you become more senior and get more control over your schedule, life becomes easier. One senior FO in my base pretty much flight-instructs all day every day; SKW is this dude's side job. Plenty of other dudes have other gigs such as real estate, etc...but that is super hard to do when you're on reserve, or a junior lineholder getting CN'd into 17-hour 4-days followed by an 8.5 hour 2-day. (that's 6 days of work in a row, of course.)...