I just had a 3 hour "layover" in OSL that was on two separate tickets. I flew from the US to OSL on Delta and then flew Norwegian to SVG. I could have booked an earlier flight to SVG and almost wish I had but I was connecting in CDG and was worried about getting from 2E to 2G. It turned out I had plenty of time in CDG.

Anyhoo, from the time I deplaned from my CDG-OSL flight, checked in for SVG and checked my bag, went through security and got to my gate, was about 25 minutes. 2 1/2 hours+ is a long time to sit in an airport with no lounge access.