Additional datapoint:
Had a ~8 hour NS > NS layover this morning (Saturday), so decided to roll the dice and take a quick trip to Leiden. Arrived from US, passing through exit immigration, taking 15 mins at 7:30am. Returned to AMS at 11am and used SkyPriority security at checkin 1-2. Initial security was 20 mins. Took a quick left to enter Non-Schengen using eGates on a US passport for an additional 10 mins.
The worst part of the excursion was the train. Many cancelled departures due to track work. Train was stuffed so full at Leiden that passengers were left at the track.