Bearded Iris with more 'substance' (thicker petals) will stay in bloom longer than others with less substance. Some of the older ones have poor substance. It is rare to find a modern one with flimsy petals.
But no matter what, even the best of them only last a few days...maybe 3-4?
I think non bearded iris may last longer.
Laetitia

I like beardeds that open their buds in slow succession since each one only lasts 3-4 days.

Thanks!