It’s up to you and your situation. For shops and commercial cleaning we recommend either a weekly, fortnightly, or monthly clean depending on your location and customer traffic. The type of business you run usually has the biggest effect on this. For our residential customers we generally recommend a 6 monthly clean to keep on top of it. However many of our customers prefer to clean their house more regularly and others prefer either to book in once a year or prefer to just call when things start to get a bit dirty.
*Note that a more regularly clean will maintain the glass and reduce the risk of severe hard water damage. A more regularly clean will also cost less as we will have less work to remove the stubborn dirt thats baked on for many years.