I once tried a 'nikkyo' on a 2nd dan, his knees startled to buckle, slightly...and then the 'nikkyo' disappeared.
As he started to rise, with a vulpine smile on his face, I stepped in with a 'direct' irimi-nage.
Wonderful. Those moments are rare in practice, because things are so predictable.
No-one can tell me about frustratiom, though...I'm married