I find LI 4 to be essential for getting control of the hand, particularly where mine are likely to be smaller than those of a an aggressor. As mentioned, the Nikyu puts it in very good position.
We also call the Nikyo an inside wrist lock. It is the lock where the wrist is locked in inward rotation, thumb is down (if uke is standing) and palm faces the outside. It helps the grab be more efficient. For even smaller hands, or teaching children who want to lock up the wrist of an adult, LI 3 is good as an alternative. It doesn't require as large a grip,and it allows you to lock up an additional joint, the base of the finger at the palm interface.
The older I get, the better I was!