The answer to 'how often to replace asphalt shingles' is that most asphalt shingle roofs need to be replaced every 15-25 years, depending on the climate, roof pitch, and other factors. Asphalt shingles are a popular and cost-effective roofing material, but they do have a limited lifespan and will eventually need to be replaced as they become worn, cracked, or damaged.
The specific lifespan of your asphalt shingle roof will depend on the quality of the shingles, the installation, and the local climate conditions. Roofs in hotter, sunnier climates may need replacement sooner than those in milder regions. It's a good idea to have your roof inspected by a professional roofing contractor every 5-7 years to assess its condition and get recommendations on when replacement may be needed.