If your canister is up to or better than an Eheim 2213 or Rena XP2, you're probably OK.
Your change schedule will be a function of your tank's bioload as altered by any live plants and fert. additions you may be into...
In other words, YMMV. That's why you need a test kit and regular use thereof. Once you establish how often a given tank 'o fish needs PWCs, schedule the amount and frequency or PWCs so that you err on the safe side.