My basic rules of thumb:
-if you want to execute a high intensity workout, you need a rest day beforehand. (100%+ of ftp)
-if you want to go long, longer, or prep for a distance out of your normal comfort zone you need to ramp to the distance. Estimate the time it will take you to go that far. Look at how long you normally "ride long". Slowly ramp up the time difference by perhaps 30min per week. Just a super rough idea. Rest day after each "long ride" or a super easy and short "active recovery" spin
-I don't think people who commute in z2 really need any off days unless planning some hiit workouts or to race.
That's about it. Feel tired? Rest. Want to go super hard? Rest before and rest after. Don't ever feel pressure to ignore the natural inclination for your body to heal.