There is no single schedule that fits every home. How quickly dust and debris build up depends on things like pets, nearby construction, how often the system runs and how well the filters are maintained.
Things that can shorten the interval
Pets, recent renovations, visible dust around registers and a system that runs most of the day are all reasons to have a professional take a look sooner rather than later.
Not sure where your home stands? Request a free estimate and we will talk it through plainly.