Of all the kihon and drills and practices in SMR jo curriculum, it seems to me that the paired form of kihon #3 - hikiotoshi-uchi - is the shibboleth. I bet that by watching a handful of repetitions of hikiotoshiuchi, an instructor could pretty closely diagnose where the student stands in their overall understanding and skill.
Hikiotoshi seems to be the shibboleth that separates super from sucky. The sucky hikiotoshi says something like "CLACK" or "tap-SMACK," while the super hikiotoshi uchi whispers something like, "ka-shwhoooooooshhh."
A few times last night I heard the ka-shwoooosh on my right sided hikiotoshiuchi but the more I tried it, the more CLACK I heard. My left side consistently said tap-SMACK.
Hikiotoshiuchi is the bane of my existence.