It is a good fertilizer to use but there are several more out there.
When I lived in South Florida from 2009-18, many orchid growers used it due to very poor quality of the water. They had to use Reverse Osmosis water systems that took everything out of the water. So many used the Cal-mag in feeding their plants.
Down there magnesium deficiencies were very common. One sign was excessive redness in new Cattleya growths and a reluctance to bloom. People felt that the Cal-mag improved-things for them. But if you have it already, then use it.
But like I said, there are others around. Over my 45 years of growing, I have used Miracle grow, Mir-acid, Champions, Orchid Plus, Dynamite and now Jack's, ALL in an even strength blend like 20-20-20. All at 1/2 teaspoon per gallon!!
Unless you are growing things like Catasetinae, Cymbidiums Or Vandas that need extra feedings, once every three weeks is plenty during their active growing season. During colder months, once a month. You can over feed many types of Orchids and you essentially get healthy leaf growers that bloom irregularly. Fertilizer is meant to support plant growth. One can easily over do it!!!
There was a belief years ago that a Blossom Booster, a fertilizer with a higher middle number like 10-30-20 was a good supplement to promote more flowers. That has been debunked now!!
The BEST THING that you can do is grow the healthiest plants you can with the best root system that you can and they will bloom like crazy. You need to repot often. Unhealthy, sickly plants with a poor root system seldom bloom. Fertilizer does NOT cure BAD growing!!!
