With a car that has a stiff suspension, the "bouncing" trick doesn't apply as it would with other vehicles. The spring is stiff enough that it will just recoil back to its position and "appear" that it's a good strut.
If you're starting to feel every bump, crack, and crevice in the road and your ride quality starts to degrade....along with bump steer and the famous protege "strut clunk" in the rear, it's time for new struts. the factory struts are great but around 80-100K miles they will start to show their age. If you find a higher mileage protege that's mainly seen highway life you can expect 120-160k miles out of the factory struts.
The Sensen struts are a great replacement strut IMO, I have them on both of my proteges and have vastly improved the ride quality of both of my cars.
Don't forget to replace your endlinks and sway bar bushings as well. they're probably toast.