As far as I can tell, it's a random pick. Over the last 3 years, 2 ETA application no problem, issue v quickly on d spot. I've had friends kena, ticket cancel la, ask High Comm for help la etc. Then this year I kena check. Sent them docs.

They dont have SLA but the general guide is:
25% response within 1 week
50% within 2 weeks
75% ETA submitted will processed within 3 weeks

Mine was within 3 weeks