My best theory is that the genetic makeup of any particular orchid plays the biggest role in how fragrant an orchid flower will be. When I used to grow zygos (which I can't now for some reason) those that were very fragrant when I bought them remained that way and the ones that weren't as fragrant remained that way. I think that is the main driver. Some are just genetically more fragrant. Another factor I think is how warm it is at the time the particular orchid produces fragrance. And lastly what kind of fertilizer has been used. A healthy orchid would or should produce a better flower and hence a more fragrant flower. Just as color in an orchid can be muted or brilliant. And when I started feeding my orchids more p and k and less n when the pbulb was about half grown, it just seemed to produce a better flower or simply flowers. Before I started doing this the orchids didn't always flower and the flowers they did produce weren't as colorful or fragrant. It's only a theory. If I had the room and energy I would get say 10 catts known for fragrance like General Patton or Karen Gubler I would test these speculations with more noses.

Thank you so much for answering! I am going to guess that the phosphorous and potassium applied at the right time are what makes the difference in my case. I plan to try your suggestion. Thanks!
Genetics, it is true, makes a huge difference. I did not realize that with orchids, one could/would redo a cross and all the siblings would have the same name (such as a Zygo Louisendorf) until I bought my first awarded orchid. I had thought all Louisendorfs would be held to the same standard, would be clones of the cross of which I had read. With fruit trees, one doesn't give it much thought as they are always grafted to ensure the fruit with a certain name is the same. A Jonathan apple tree or Redskin peach will always produce just what I expect.

LC Canhamiana - 2nd years flowers.
 

This is the second annual flowering of the Canhamiana. It has 7 flowers on 2 inflorescences and this year I detect a strong pleasant fragrance.

Very nice DC. My Canhamiana just bloomed also. Very nice flowers. I haven't detected a scent yet. Yours are very nice.

Really lovely!