There is a time and place to count those smallest units, and to get them metronome-precise. But that time and place is not rehearsing the St. Matthew Passion with a group of good musicians. Those musicians should have already internalised the body of rhythmic patterns that can happen at that level, so that practice, in an ensemble, is about putting these patterns together in musical ways, sometimes smoothly, sometimes sharply articulated.
Here are three pages from a worksheet I have used with young musicians. There is nothing particularly profound here; others can certainly make up more useful or elegant layouts of the same material. It's just a collection of patterns within single metrical feet — notated here as quarters and dotted-quarters — followed by a number of metres composed by adding these quarter and dotted-quarter feet togther. The idea here is to practice performing each pattern so that they can be sight-read and played or sung precisely and fluently, and then to compose and/or improvise in each of the metres, substituting in the various single-foot patterns. This is closer, methinks, to the way musicians really read and play music then the count-every-single-subdivision model used by the Very Famous Choral Conductor. This worksheet goes up to five-fold divisions of a foot. For less advanced students, one might well get along with stopping at division of the foot into four, so the quintuplet patterns have been somewhat segregated on the page. More adventurous students will most likely find their way into more complex divisions and metres without outside assistance.