There is little consistency, unfortunately. I had a few horror experiences when travelling on one of my passports which is not eligible for Global Entry and no SS picking me up. In one instance a couple of months ago I was in the queue to the kiosks for about 1 hour (ie: 1 hour to get to the kiosks plus then another 20 minutes to get stamped and exit). Other times I was in the baggage hall within 5 minutes.

One key variable is whether anyone in your group will get the dreaded “X” on the kiosk’s receipt. That can happen even if you are on ESTA and can depend on a variety of factors. That would mean another - usually long - queue to see an immigration officer, which could take AGES. So, my advice would be to build generous contingency if you have other plans afterwards.