I ignore most of the directions about when to arrive and use my judgment. There are airports that tell you to arrive X hours before your flight and you get there at 4:30 AM for a 6 AM flight and nothing is open. My home airport is MCI. Does it make sense for me to arrive 2 hours before for an international flight (generally a connection in ORD) when I can use the Elite check-in line and it takes 15 minutes to go through "security"? No.

As for DEL, I actually did get into the airport earlier than 3 hours before the flight- maybe because I was coming in from BLR and connecting, I don't know. (The international and domestic terminals are a few miles apart.) They actually restrict which flights can go through "security" and I've found it works out. The lines aren't half as nightmarish as they were in 2004 when I first flew from there and anyone could get into the line regardless of how soon their flight was leaving.