This subject is deep!
If you are happy with the growth of your plants there is no reason to change fertilizers. If you want to improve on what you have there is every reason to change.
Plants need a constant supply of many different nutrients (elements) to grow at their best. They don't "eat food" just once per month. They need a constant supply of nutrients to grow at their best. Natural soils have the ability to hold nutrients like a "food bank". Plants send out roots to make withdraws from this food bank. If the bank is full the plant takes what it needs at that moment. If the bank is empty the plant does the best it can with what it can get, but never grows as well as when the bank is full.
The ability of your potting soil (mix) to hold nutrients will dictate how often you should fertilize. Most orchid mixes have very low nutrient holding capacity. So logic and plant science tell you you need to fertilize often. Commercial nurseries go to great expense to add nutrients to their irrigation water every time a plant gets water. They don't do this because they have extra money to spend. They do it because it has been prooven plants growing in artificial (non soil) mixes respond favorably to a constant supply of nutrients. There is no doubt about this.
The ratios and balance of elements play a huge factor in plant growth. It is not enough just to have plenty, there must be balance between the elements. A high level of one may mean you need a low level of another or vice versa. This relationship is where fertilizer manufacturers get the valid chance to make claims they have the best formula.
Fertilizer brands and formulas can be very confusing. For the most part all the brands use the same materials to make their product. They simply add a little more or less of some elements and say theirs is the best. And one is about as good as the next. EXCEPT for those that contain Urea. Urea is not intended to be used on delicate plants. Urea is the cheapest source of Nitrogen available to fertilizer makers. I would avoid using any fertilizer containing Urea on orchids. Urea is intended to be applied directly to the soil and quickly covered or watered in. The Nitrogen in Urea quickly turns to an Ammonia gas when it is in contact with air and escapes to the atmosphere becoming unavailable for the plant. Urea can give off ammonia gas even when it comes into contact with foliage. Once mixed with water Urea is somewhat stabilized and this is why fertilizer makers can get away with using it in a "ornamental plant food". Leave the container open and urea becomes a wet glob and begins to release Ammonia. Urea in a "plant food" is a big flag that the manufacturer cut corners.
MSU fertilizer formulas are the result of specific university trials done with
orchids to determine which elements an orchid needs to grow at optimum rates. Their trials determined all the important elements orchids need and at what ratio they are needed in. For this reason alone this formula is likely the best choice for the home grower.
With a constant supply of nutrients your plants will grow at their best, often much faster and better than in their natural habitat.
Here are a couple Paph. Rachael Ann Booths, 5 months from flask. 3 inch pots with 6.5 LS. These seedlings have been watered with fertilizer solution everyday form day one.
Here is a Phrag. besseae hybrid 5 months from flask also watered everyday with "fertilizer".
Certainly orchids will grow without much fertilizing. But certainly fertilizer everyday does not hurt them.
I have around 1000 orchids, and use less than 2 pounds a year! Granted, lots of them are seedlings. I don't fertilize very heavily, but I do give them fertilizer with almost every watering.
