I just replaced a chain and cassette just 'cause it seemed easier than cleaning the unbelievably gunky older ones (neither of which were too too worn) and this is basically the beginning of the dry season so I'm hoping for 3 months of no maintenance. I'd just rather start the dry season w/ a new setup, get the best performance out of it while it's nice out, than run through the nice months w/ the nasty one that requires frequent maintenance and then still find myself switching them out once the rains start in the fall.