The need for new running shoes depends more on mileage and wear rather than time. Generally, it's recommended to replace your running shoes every 300-500 miles to ensure optimal support and cushioning. However, if you notice uneven wear patterns, discomfort, or decreased performance, it might be time for a new pair. Annual replacement can be a good guideline for casual runners, but more frequent replacements may be necessary for those who run higher weekly mileage.