I guess it depends on how detailed the developers are in connecting the taxiways to the gates. Especially when they or another community developer creates a custom GSX profile for that airport. But yes, there are some custom airports that were poorly made that the GSX pushback had a hard time stopping at the right position at the right heading. But generally speaking if you try GSX pushback and let it play out until the end and it stopped perfectly. Then it should stop correctly everytime after that for that airport.
About the procedures, what I usually do is as follows:
- Request boarding from GSX on auto mode, this will start with the crew, then call on the catering truck and fuel, then start boarding the baggage and the passenger after a set amount of time.
- While that’s running in the background I start with setting up the aircraft procedures, battery, ext power, APU, etc.
- Then ask for departure clearance from ATC. This will give you the squawk code as well as the runway to depart and first step altitude. Set this up at the panel.
- Then I start entering the flight plan, with the assigned departure runway, SIDs, STARs, arriving runway and approach and all the performance calculations needed in the FMC/MCDU.
- Once they’re all loaded and the pax are finished boarding and no other ground service connected. Request clearance for pushback via GSX.
- When the GSX pushback gives you the clearance for engine start, start the engines in sequence.
- Let the pushback finishes on its own, let them disconnect and wave that the pins are removed and good to go. Check if your engines are all started and stabilised.
- Once you finish with the after-start checklist and ready for taxi. Then you ask ATC for taxi clearance.
- Turn on taxi lights once you have this clearance and taxi to your runway.
- At the runway, contact ATC again for take off clearance, once given then you move to the runway, turn on strobe lights and landing lights, and take off.
I have lots of videos in my YouTube channel that you can take a look on how I do it.