I've read the same as Celia and have not had my a c ducts cleaned, but I don't have forced air heat for heat. I'm also not allergic to dust.
I looked for a good source quickly and found this from Canada. It seemed to summarize what a couple others were saying. It is for patients with asthma, but I think the principles would hold for us or maybe be even tighter.

It doesn't sound like you suspect mold, excessive buildup of dirt, or rodents which is when they advise it.
https://asthma.ca/wp-content/uploads/2017/08/asthma_duct_cleaning_eng.pdf