In our dojo we have a fixed senior line and a rotating junior line. The senior student is expected to help the junior understand what is happening, help with the technique and keep the training rythme. Sometimes that requires more verbal, sometimes less. Sometimes the senior speaks too much, sometimes too little. It's a learning experience for both
That's exactly what I wanted to say, but you saved me the time and trouble of forming the words. This method of practice is especially useful if you have a large batch of beginners (20 or more) coming in periodically.
Nevertheless, I like to throw the higher-ranked students a bone and let them practice together at the end of each training session (about 30 minutes).
I also publicly thank the higher-ranked students for helping to teach the new students, lest good deeds go unapprecieated.
Also, I often demonstrate techniques using a beginner so that the higher-ranked students will see how to practice with a new student. (It's not about showing off — right?)
There's a lot of talking, but it saves me an awful lot of trouble, and I'm quite amazed at how quickly everybody learns. It also gives the higher-ranked students a sense of value and gives them the opportunity to learn by teaching.