Another thing worth mentioning is that a lot of airlines now seem to check all their flights which are departing over a period of time, maybe all flights departing within 3 hours of each other. There will be maybe 6 check in desks open and everyone has to join one queue regardless of where you are going and check in on whatever desk becomes free.
If you have left it a little late to get there you may have to try and squeeze in to the front of the queue as there may be 100 people in front of you whose flight leaves in 2 hours time whereas yours departs much earlier than theirs.
You never really know if this is going to be the case until you get there.
Many business travellers do tend to turn up later for flights as they don't like hanging around in airports. This is a risk you take with regard to any delays getting there. Also bear in mind that check in desks will close generally half an hour before the flight departure time, 20 minutes at the very latest. You often board the flight more than half an hour before departure.