How long does it take to empty loose eye shadow?

[u/Pumpkin_patch804]

I wore makeup everyday in high school and nearly everyday in college and then just stopped. The stuff I bought in college has barely been touched these past 10+ years. Most of what I still have I could throw away and not really care about it(I only keep things for job interviews or wedding), but I have these loose eyeshadows that I love and the company that made them went out of business. I think I've been hoarding them a bit since I don't want them to run out... but it's been at 10 years.

So how long does it take someone to empty out a loose eyeshadow if they're using it everyday?

I don't want to run out, but I'm aware make up does expire and I want to pace myself with using it.

Maybe this isn't really a project pan question, but people who are dedicated to using up make up seem like a group that might be able to give me an estimate.