Re: teachers can no longer study?
A senior aikidoka who used to teach occasionally at our dojo had a process for this. He'd demonstrate the technique, let people pair up, and then he'd circulate. If there were an even number of students, he'd practice with each member of the pair, doing the technique and receiving it. Then he'd move on to the next pair.
If there were an odd number of students, he'd practice with the odd man out. Then he'd break up a pair, send the extra guy to practice with the odd man out, and practice with the other half of the pair, circulating until he got to everybody.