The only product I think I have ever thrown away was one of those huge MAC face and body foundations, and only because it had separated to hell and smelled 'off' after living in Indonesia for 3 years. Bought it in Canada and took it there. Retard. Never wore it there because it was so bloody hot. The heat and humidity there murdered it, right in the bottle, even though it was stuffed under a bunch of stuff in a suitcase. Even my beautiful leather jackets grew literal MUSHROOMS there *bleh*
I have my brushes from MAC which are around 15+ years old, and even some of the shadows I bought *with* them at the time which I still have never used up. I still use them from time to time, actually, just not enough to actually use them up. I've hit pan on one and might get a replacement (it's in one of their palettes) but will never toss anything out which I will still use. I'd rather give it to somebody. I had over 175 pigments or so at one point, which I knew damn well I would never in this lifetime use up, so I gave half of them (half of each) to a friend, which she ended up using for art work, etc LOL
I really don't understand why you would throw them out after 3 years if they looked, applied and smelled fine. That's the other thing. If they still apply fine, why would you toss them?? *gahh* Next time ship them all to me LMAO I'll give them a new home!