If screens are taken care of properly, they can last a lifetime. This is especially true of retensionable screens. The Mesh on retensionable screens can be tightened as necessary, essentially making them "new" again.
Rigid frame screens (wooden and aluminum frames) can also last for a very long time if just a few simple precautions are taken with them.
You should adopt the following practices to increase screen longevity:
Clean them carefully and thoroughly after each print job.
Reclaim them as soon as is practical. (removing old emulsion can be difficult).
For long term storage of unused wooden screens, store them in air-tight containers (such as heavy duty trash bags) because wooden screen frames can warp from humidity.
Most importantly, handle all screens with great care. Once you get a rip or tear in the Mesh, the longevity of the screen will decrease substantially. To increase the life of screens with small Mesh tears, tape over the ripped portion with durable screen tape.
