Hey, nice thread. Just started doing this stuff this week. Did Ams- her - cdg - ath - oslo.

AMS : should be easy. Comes out next to boarding so you can go right in.
HER : dont know if you could, i stayed overnight
CDG : should be doable. Got out in T1. Could turn left, go through security check and back to boarding. They do extra pasport checks for incoming planes from greeces, so if they hold you up you could be in trouble. I stayed for a croissant so I cant confirm.
Athens : Think you can do it. Before bag reclaim I saw a stairs right back into departures. Cant confirm that.
OSL : Dont know if you can. On previous flights, i saw specifiek transfer area's, but didnt see any this time.