I am enjoying my GS off time. Yesterday my friend finally fixed up the rings to their permanent place and today I did some long forgotten stuff: pushups, flys, straight body raises, pullups in L and some other elements. My wife joined me in this venture and it seems she got a good workout.
Rings are unstable and that's why anything you do on them has double effect. Flys, for example, load the whole anterior chain, and after 10 reps abdominals are simply burning. Hence the time saving effect: the chest and the gut are loaded at the same time. The same is true for pullups in L: hang on the rings, lift your legs to 90 degrees and do pullups. If normally I can do 10 - 12 reps on the bar, in this position I can barely squeeze 5.