I know it's time to replace shocks when I'll hit a bump on the highway, and the thing is still bouncing by the next exit lol

That's a bit of an exaggeration, but when the ride gets too bouncy, or the car really nosedives under hard breaking, time for new ones.

 

Yes, bad shocks are a real problem and a dangerous at that.

Nice old Bilstein video. The yellow Golf has it's shocks at 50 %. Vs. a new set of a sports suspension.


nice close up views on what happens.