I have also struggled with keeping the lessons short. This past year I tried breaking the lesson down into 3 parts. I used the idea of "I do- you listen" (teacher model) for the first mini lesson, then after round 1 we gather back and it is time for "we do" (guided practice) then back out we go for round 2. Next we gather back and it is time for "I do independently" or (independent practice). It helped me last year.