Most professionals recommend you to have your gutters inspected at least 1-2 times a year in the spring and fall.
But where you live also plays a factor. For gutter cleaning in Seattle, where it rains the majority of the year, you might have to have it done more frequently, especially if your home is beside trees that shed often.
Or, if you live in a Minnesota where it gets below freezing temperatures in the wintertime, your primary concern would be checking your gutters right before winter to prevent any water blockages from freezing up and cause damage to your roof.
Another instance for when you should clean your gutters is after a severe weather storm. Leaves, branches, and debris might find their way to your roof and gutter, causing sudden blockages.