Most of our cattleya last 4-6 weeks, but many things can shorten the time.
When fall winter flowers open early in the Florida summer I lose them in 1-2 days outside (up to 104 degrees) yet the same plant will stay in flower 4 weeks in doors in air conditioning. Temperature dehydrates the flowers.
Buying a bare root in spike will never last more than a couple of days. It has been stressed too much.