[Twisted-Python] scheduling timers with long intervals

I have a server that is running for weeks without restart, under significant load. We are considering adding a function to it that requires setting long timers like twisted.internet.reactor.callLater(604800, func) i.e. scheduling events one week ahead. There will be up to 500 timers active at any given time. I do not know how the scheduler works. Will having these timers with very long intervals significantly tax the performance, since the reactor will have to check on their status with every churn of the reactor loop? Thanks Alec