I toss mine when they become discolored or worn looking. I don’t think you can put a timeframe on it. Some more expensive wood scoops last longer. And it really depends on much you use them and how well you take care of them.
I try to clean them thoroughly right after they’ve been used and never soak them. But every now and again I find one that has been immersed in water in a pot in the sink for hours… if it doesn’t clean up and dry quickly, it gets tossed.