Most articles on this say twice a year and leave it there. That’s a guess dressed up as advice.
The real answer depends on two things about your specific house: what your irrigation is doing, and what’s growing over you.
Start here: is your landscaping hitting your windows?
This is the biggest factor and it’s the one nobody thinks about.
If sprinklers, drip spray, or lawn irrigation put water on your glass, mineral deposits start building within a day or two of every cycle. Left long enough, that buildup etches into the glass permanently and no amount of cleaning brings it back.
If that’s your house, frequency isn’t about looks. It’s about keeping deposits from ever getting thick enough to do damage. More on hard water
If your irrigation stays in the beds and off the walls, you’ve got much more freedom and you’re really just cleaning for appearance.
Second: what’s over your roof?
Heavy tree cover means pollen in spring, sap and debris through summer, and leaf litter in fall. That’s a different kind of dirty from mineral, and it’s more forgiving, because it doesn’t damage anything. It just makes the glass look bad faster.
Around here that means older neighborhoods with mature canopy, Fair Oaks, Carmichael, East Sacramento, and the foothill lots up in Auburn, tend to want more frequent cleaning for appearance while newer tracts want it for hard water protection. Same schedule, different reason.
A working answer
Quarterly is what we’d suggest for most houses in this region. Four times a year keeps mineral from establishing, keeps each visit short, and means the glass never gets to the state where it needs recovering rather than maintaining.
Twice a year works if your irrigation doesn’t touch the house and you don’t have heavy tree cover. Spring and fall.
More than quarterly makes sense when sprinklers hit the glass directly and you’re actively protecting it, or when you’ve got a lot of ground floor glass that gets used, touched, and leaned on.
Once a year is what most people default to. It’s better than nothing and it’s enough for a shaded house with well-aimed irrigation. It is not enough to stop hard water in a sprinkler-heavy yard, and that’s the situation where waiting costs you glass.
We’ll tell you honestly after the first job which of these your house needs. If quarterly is more than you need, we’ll say so rather than sell you a schedule.
Businesses are a different calculation
Commercial glass is about traffic and visibility rather than sprinklers.
Weekly for busy retail frontage and most restaurants, where doors get touched constantly and guests look at the glass up close.
Monthly for offices and quieter locations set back from the street.
There’s a cost argument too: glass cleaned weekly takes a fraction of the time glass cleaned twice a year takes, because nothing has bonded to it. Weekly is 15% off and monthly is 10% off, with no contract. Commercial →
Things that change the answer
Selling the house. Get them done before the listing photographer, not after. Pre-listing →
Just finished construction or a remodel. Different job entirely, and it needs doing once the trades are out. Post-construction →
You’ve never had it done. The first clean is the heavy one. After that you’re maintaining rather than recovering, and every visit after is easier.
Second story you can’t see. Upstairs glass is where problems hide, because nobody looks at it. Worth having someone actually check it. High and vaulted →
The short version
Go outside while your sprinklers are running and watch where the water lands.
If it’s hitting your windows, get on a quarterly schedule and go adjust those heads. If it isn’t, twice a year is fine and you’re only cleaning for looks.