Update: Tried Artha Gading today, got my location on and apps ready to go as I walked from my car to the entry door. Scanning the QR code (posted on the door) was smooth, took mere seconds for the confirmation 'berhasil/success' to appear. Closed it too quickly when the 2nd security asked to see it, I just said I already scanned it outside, she let me go...note to self, make sure to show to the security before closing app.
Also had to scan again on the way out. I'd say as more people are getting used to scanning (and preparing their phones before they're at the front of the door), the lines should be shorter. I probably only had about 4-5 people cueing (more like crowding) in front of a qr code.