First one here would rile a lot of colleagues, it would also depend on if you are single, which I am, so was able to get QFF SG 3 years in a row. with no wife to moan to, or moan with, or to being asked a lot of questions of.
And have a skill set (as mentioned above) that people want and need, to be able to fly then and there, book and fly within a weeks notice which would put you into a higher fare class and more SC earn, discY vs flexY for eg, and might not necessitate overnight stays to make it worth it/worthwhile financially, ie, fly out of your home city and back again in the evening, saving on hotels.
Also if you have a car licence, (heh, not everyone has one), being able to pick up a rental car and drop off on the spot, granted having uber or a taxi account app helps too.
Being fit, and HLO is important too, several times ADL - SYD - NZ necessitates running, through the airport, to get from the plane arr gate at T3, to get to gate 15, and then up from the bus drop off point at T1, across the int check in area, and onto outgoing immi and security processing. Linked PNR ADL - SYD - NZ does not leave a lot of time for the lounges, ie, dep ADL at 2.55pm, get to SYD T3 about 5pm or so, and then rush to T1 by 6.30pm for the flight to CHC/WLG/AKL.
On SQ ADL - SIN - HND, the SIN transit time is 2.5hrs or so, others are 7 hrs, a bit too far apart.
Covid did put a stop to a lot of my NZ flights.
Though I only travel for leisure, not work.