Your improved growth shows the importance of adequate nitrogen in your fertilizer.
I use a 12-1-4 and a 11-1-6 around my yard and I am quite happy with the buds my trees make.
The proportions of nutrients the tree ACTUALLY use is roughly 12-1-4 with calcium being 12, magnesium being 3 or 4, sulfur 2, and a long list of micros.
When the nitrogen source is as nitrate, potassium is needed in the active chemistry used by the plant to absorb the nitrogen, so a nitrate based fertilizer should have nitrogen and potassium levels roughly equal. If a fertilizer has its nitrogen in the form of ammonia or as amines, then the amount of potassium needed is only the 4, required for other metabolic processes in the plant.
These nutrition ratios are surprisingly stable across all species of plants. Seaweed to sequoia, they all need roughly 12-1-4, with only minor percentage changes for individual species.
Fertilizer companies are in the business of making money. They don't care if it works, they only care if it sells. So if enough consumers ask for a "balanced blend" meaning a 10-10-10, they will make it and for the farmers they will make a 12-1-4 or a 12-1-13. THey sell much more of the "modern nutrition formulas", much more in terms of thousands of tons more of the modern formulas.
So that "Balanced formula" 10-10-10 is really imbalanced to what the plant actually uses.
Interestingly, the ratio of nutrient usage does not change, winter, spring, summer, autumn. It remains constant. What changes is the total amount needed. In slow growth in winter, you only need a very dilute solution of a 12-1-4. In late spring and early summer, you need a much higher concentration of 12-1-4. But the ratio the plants actually use remains constant.