Frictionless world

In a frictionless world a 3:1 mechanical advantage is a true 3:1. Well in our wourld a 3:1 is less than that with good new pullies and a brand new rope. As wear on the pullies and rope ages the advantage goes down.
I know a pully is really about .85-.90 to 1 for the friction of bearings and such. I was told the friction of a carabiner is about .5. If all carabiners wer used in a 3:1 the true MA would be about 2-1.5:1. This just seems really high for a carbiner to be about about .5. Has any math blaster measured this? It seems it should be lower.
Thanks

Over the limbs and throught the leaves!