Depending on the application, shocks can be anywhere between 50-50 and 90-10, with the greater damping on rebound. Shocks stiff on compression make for a harsher ride, extension damping serves to limit oscillation and control the unsprung weight.
The only exception I know about was a drag racing front shock that served to hold the front end up for weight transfer to the rear, which had almost no damping on extension and was very slow to come back down.
Tom Test
Itasca Spirit 29B