When to throw nail polish away?

[Lagirl20]

I’m having a clear out. I have several bottles of nail polish I bought in 2014/15. Most have separated in the bottles, but I can shake them back to life. I’m assuming they’ve expired as they’re several years old now

• plus formulations have probably improved a lot so I should probably throw them out? Thoughts?

I throw mine when they are gloopy or if they dry streaky. I don't go by how old they are

I have some from the 90s that still work. Yours are fine if they're still usable.