Apply fertilizer at the rates required to meet your management goals. The appropriate fertilizer and rates to use are determined via a soil test and knowledge of the site and plant requirements, not a distributors "recommendation".
Do not tank mix herbicides & fertilizers without researching the potential reactions between the two and/or in a manner that is inconsistent with label directions. IMO, both fertilizers and pesticides should only be used when a need has been established, not because it is what everyone else does or because it is easier. Always look for alternatives to chemical applications (ferts or pesticides) and use those alternatives whenever possible.