Excellent information, as usual, Ray. I do believe that a rapid wet/dry cycle (frequent watering and fast drying) is the best way to grow any orchid that has a prominent pseudo-bulb. Unfortunately indoor, windowsill growers have a difficult time achieving that type of culture so they need to adjust their techniques to fit their environment. Needing to work for a living can also make it difficult to water frequently.
As far as water quality, I personally believe that there are five macro-nutrients rather than three. If a grower uses pure water on orchids, I believe it's important to provide Nitrogen, Phosphorus, Potassium, Calcium and Magnesium (and small amounts of micro-nutrients). The reason Calcium and Magnesium are often excluded from fertilizer formulas is that those two elements are present in many, maybe even most, municipal water supplies. Cal/Mag fertilizers are very important when using pure water. I totally agree with the frequent use of low concentration fertilizers. Fortunately I grow my orchids outdoors in open wood baskets or on mounts so fertilizer accumulation is never a problem.