Ok, I have been thru Schiphol before but a while ago and have a tight connection this time. So I am not confused, when you arrive from the US to Schiphol you have to find the gate your next flight is at, but you have to go thru the customs and secruty line again before you can get to the exact gate?
If your connecting flight is to a Schengen country, you have to pass through immigration and security to get to your gate (the security screenings at Schipol are usually done at the gate). For non-schengen destinations like the UK and Ireland, you don't pass an immigration checkpoint, but still have the security screening. Tight connections usually aren't a problem at Schipol.