How often should I change my gas filter, considering the myriad of factors that can influence its efficacy and longevity? Is there an optimal timeframe that one should adhere to, or do fluctuations in usage patterns necessitate a more tailored approach? Furthermore, are there specific indicators or symptoms that suggest the filter may require more frequent replacements, perhaps due to increased particulates in the gas system or operational inefficiencies? For example, could a noticeable decline in appliance performance or unusual noises signal an urgent need for a replacement? On the flip side, might prolonged intervals between changes lead to detrimental outcomes for the overall HVAC system? What guidelines do experts recommend in terms of mileage or operating hours, if any? Lastly, how do seasonal variations impact the recommended frequency for gas filter changes, especially in climates that experience extreme temperatures? These are all pertinent considerations to ponder.