just unrelated addition. I was refused (arrival) immigration at Terminal 3 when I arrived at Terminal 2. The reason was rather stupid: we don't have your name and flight number in this terminal. I did this several times and it was ok until last year. Maybe it's because of baggage reason that they blocked me from doing this (but I made it clear to him that I have no baggage and I am in transit). Still refused.

Therefore my advice is to use the terminal you depart/arrive in.