You do need a system for worming but having said that, I wouldn't recommend the routine medication of any animal.
I'm a firm believer of ''if its not broken, don't fix it' Creatures having worms is a perfectly natural state of afairs. So your chickens have a few worms in their system, so what ? IMO, unless the burden is at a stage where you feel that the animals health maybe being affected, then I wouldn't worry.
To my mind, there's a big difference between keeping on top of the situation and routinely scourging the animals system. You do need to give wormer to pigs from time to time but you must remember that wormer is basically a poison. Its also good practice to rotate the wormers that you use.