The situation in Europe is unlike anything I've seen. Going through security at Schiphol airport today took about 3 hours (just the security, not everything pre-flight). The line first spun around a wing of the airport public area, then outside for a good 800 metres or so both ways, then back inside and the entire top level of the public departures area.
Hundreds of people are missing their flight every hour, so the lineup at the service desks is also very long - but moves much more slowly, so you would need to spend another 3 hours waiting in this one, hoping by the time you reach the staff, there is still a flight with a spare seat to take you to your destination before the day ends.
The flights that are leaving are about 30-60 minutes delayed. Airlines have to carefully balance airport slots with the count of passengers missing flights, probably ensuring they can ideally rebook them on a later flight.
It's not just in Amsterdam, the same problem has spread to all major EU airports. So be very careful, if you can take even an all-day train instead, believe me it would be worth it. At least you can sit down comfortably, drink cheep beer and use the toilet instead of lining up all day. If train is not an option (ie. leaving EU) - then be as early as you possibly can and/or are allowed to (in my case, Schiphol security doesn't let anyone in unless their flight is in the next 4 hours).
Security queue, about 40% of the way through the entire thing (but midway point of the outdoor section). That tent itself is many hundreds of metres long. I'll never complain about aussie airports again!
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Flying KLM - to their credit, when I was able to talk to the ground service desk staff they were very helpful and efficient in sorting everyone out.