It’s up to you how often to clean a glass pipe. Our tip would be to clean your marijuana pipe after every smoke session.
The more often you clean out your marijuana pipe, the less difficult it will be. Built-up residue can be a pain to remove. If you need to deep clean your glass pipe, you can use a homemade solution with some isopropyl alcohol and some salt, and let your glass piece soak in a bag of a mixture of the two. After soaking, rinse thoroughly multiple times until completely rinsed.