I have always thought that 16-16-16 was good for all lawns, but after close examination of the bag's instructions (always a good idea!) I see that it says that it is for starter lawns. I'd rather avoid the hassle of keeping different fertilizers for spring, summer, and fall feedings, so is there one type that I can apply consistently throughout the year? Also, how often can I feed it? At this point, the lawn (even though I used sod a few years ago) is struggling, and I'd like to apply it as often as I possibly can, to get it to grow healthy. My bag of triple 16 says every 4-6 weeks, but that sounds like an awful lot of fertilizer, and I'm wondering if they're just trying to sell lots of product.