Yabia:
Why did you ask what Yotzros were if you clearly knew the answer? Just so that you could critique whatever response you got?
I have never heard of Sphardim saying yotzros on shabbos arba parshios, or shalash regalim. I could be wrong. Apparently, you’re the expert.
Laskern: the rule of thumb seems to be:
Call inserts into the birkas shema “piyutim”
Call inserts into krias hashatz on chagim “yotzros” (misnomer because the word comes from yotzer ohr)
Call inserts on Purim “krovetz.”
I don’t think there’s any rationale to that pattern; it just seems to be the trend.