Power steering hoses should be inspected at least once a year or every 12,000 to 15,000 miles, whichever comes first. Regular inspections are crucial to identify any signs of wear, leaks, or damage that could lead to steering issues. During these inspections, look for cracks, bulges, or any fluid leaks around the hoses and connections. 
Replacement of power steering hoses is generally recommended every 100,000 miles or if any significant wear or damage is detected during inspections. However, the exact timing can vary based on the vehicle's make, model, and driving conditions. Vehicles that are frequently driven in harsh conditions, such as extreme temperatures or rough terrains, may require more frequent inspections and earlier replacements.
If you notice symptoms such as difficulty steering, whining noises when turning the wheel, or visible fluid leaks under the vehicle, it may indicate a problem with the power steering hoses that requires immediate attention. Addressing these issues promptly can prevent further damage to the power steering system and ensure safe vehicle operation.