For Exteriors homes this is a very relative question. The largest variables are sun and rain. Other big factors are prep work from the initial job, and was the proper amount of paint applied? Most of the time painters skimp on the application not getting enough product on the surface. I see allot of “painters” stretching and pulling the paint across the surface instead of applying it to the surface and leaving it to dry, instead they over work the paint and thin it out resulting in a thin coat with brush strokes or orange peel depending on what they used to apply brush or roller. You may even see through the paint when it’s really thin, typical for builders grade paints or one coat rush jobs. So all things being equal you should expect 4-6 years on an exterior in the Northern Virginia, NOVA, Washington DC, and similar climates.