How often should I use weed and feed on my lawn to ensure optimal health and vigor? Is there a particular season or specific conditions under which this combination of herbicide and fertilizer is most effective? Would applying it too frequently result in adverse effects on grass growth or soil composition? Additionally, are there particular types of grass or environmental factors that might necessitate a more tailored approach to application frequency? Would the local climate, soil type, and existing weed pressures dictate a need for adjustments in my routine? Is there a recommended schedule for application that balances the nutrients provided while simultaneously managing the invasion of unwanted plants? Furthermore, how does one ascertain the efficacy of the treatment, and are there signs that suggest I may be over- or under-treating my lawn? What precautions should I consider to avoid damaging desirable vegetation during the application process?