I am also a kindergarten teacher. We spend the majority of our day in small groups. I teach small groups for reading, math, and rti. I have found that while teaching in small groups I can help students with misconceptions and give those students that get lost in a large group the help they need.
Great question. I work with all students in small groups at some point if they need enrichment or extra help. The students don't know what the other groups are working on.