Back in my CC days with BA, I commuted for a number of years. From IAH-LGW and NRT-LHR. I was able to do this because I was on a 33% contract. I would fly to LON, do three weeks of flying. This was usually 3-4 trips depending on duration. I would then stay with friends, family and the odd B&B between trips. After the last trip, I would then fly home for 6 weeks.
A number of crew as well as management commute from faraway places such as SYD, CPT, LAX, BKK etc. As far as I know they are on part time contracts or are able to manipulate rosters to group their days off into large blocks.
All flights are standby ID90 and the chances of getting on depend on where you commute from. I always did my homework before just turning up at the terminal. I would also arrive the day before my first duty and never suffered from fatigue. The vast majority of flights, I would be assigned a seat in Y (usually a middle at the back) but it would either be changed at the gate or onboard by crew who recognised me (usually the Japanese ICCs) or were trying to sort out a seating issue.
Only once can I remember not getting on and couldn't get to work for about 3 days due to disruption. I ended up taking leave. I missed more flights living in Brighton and dealing with the M23/25 than I did from commuting.