I studied greenkeeping in some depth and went on to manage different types of sports surfaces, in many differing situations. What I hope I learned may of be of some use in the following analogy.
1) If it ain't broke, don't fix it, but find out everyithing about your current state, maintain it and make sure it doesn't deteriorate. Improve if you want to or have the time or inclination.
2) Keep a sharp eye out for problems. Use them to find out what is wrong. In my case, I used weeds as indicators. i.e. clover would mean low nitrogen,
2) Feed little and often.
Finally however, I would like to add that soil pH will directly relate to your yield if you are trying to grow to maximum efficiency. However, small drifts will have little bearing unless the plants are showing a deficiancy. Also remember that an excess of one nutrient can prevent a lock-out (plants ability to absorb another) nutrient.
An often-encountered example of this is an excess of phosphate that makes the roots unable to take up Magnesium. The result has the appearence of Mg deficiency but cannot be cured by applying more Mg as it's not getting to the source of the problem (excess Phosphates). Unfortunately. Mg lock-out is often mis-diagnosed as Iron deficency, which, in the case of turf, results in Fe sulphate applications which drops the pH and compounds the problem
I guess what I am trying to say is it depends on how far you want to take it, how much you want to learn, and if and how much you are bothered about the extra bit of yield.
