I'm more of an "every couple months" diffuser cleaner or when it isn't quite working correctly, but your Diffusers will last longer and better if you take care of them! Trust me.
Standard diffuser recipes run roughly
500 ml of water, use 15-20 total drops of essential oils
300 ml of water, use 10-15 total drops of essential oils
100 ml of water, use 3-6 total drops of essential oils
These will vary depending on the potency of your oils. For example Lemongrass and Cassia are very strong smelling oils so you can use less. Start with the smaller number of drops and add more if you prefer.