I think there are some unintended consequences of the way ornamentation is notated in Western music. Often the ornaments are indicated with some kind of abstract symbol or with tiny “extra” notes (like grace notes), located visually outside of the music’s rhythmic structure. This sometimes leads less-experienced musicians to the conclusion, consciously or otherwise, that the ornaments do not have precise rhythms. Sometimes music teachers feed this problem by explaining the rhythmic aspects of ornamentation in a vague or misleading way.
For example, many of my saxophone and oboe students are initially stymied by this moment in the first of the Ferling 48 Famous Studies:
An unclear but common way to explain this is to indicate the pitch pattern of the turn—up a diatonic step and back down, down a diatonic (or maybe half-) step and back up—and then say something to the effect that these notes “steal” time from the F-natural. The grace notes in the next measure can be poorly explained by emphasizing that they go “on the beat.” These explanations aren’t factually incorrect, and make some sense to someone who already understands what the end result should sound like, but leave a lot of unanswered questions for students who are less experienced with ornamentation.
To be clearer about the turn, I think it helps to think through exactly how many notes have to be played in the space of the F-natural (five) and some possible ways to fit them in. Here are a few:
