In my case I look out for the immigration line that moves fast meaning the officer checks quick n does not ask questions n on the other hand some officers ask too many questions n it becomes a probelm
What I normally do is lookout when u r linning up at the immigration line watch which immigration officer is quick in stamping the passport. Some r slow n ask too Manu questions whereas some officers don't bother asking questions n just stamp the passport n let u in however now with the new automated check in online u will get a reply before entry if u approved to enter n your duration of your stay