Someone trained in Ichi Gan shall always have noticed each and every opening the attacker offered. The technique would then be struck and stunned on first contact. An arm dislocated on second and a rib broken before the execution of the throw.
A sempai (advanced student) shall always "see" these openings during normal training and choose not to take them so as to be capable of executing the technique time and time again without injury to the uke. But they are always there.
A true martial artist is one with the ability to kill but chooses not to.
Old school
You do not defend while attacking, you get hit in the face.
You attack with little commitment, you get hit in the face.
You "assist" in the technique, you get thrown out of the dojo.
Saito shihan: Flowing techniques must not be attempted until 3rd dan.
Tada shihan: You must never execute / demonstrate techniques beyond your ability
ICHI GAN 一眼
First, the eyes. Learn to observe, watch everything closely and develop zanshin (awareness) before, during and after an encounter.
NI SOKU 二足
Second, the body. Move the body using proper alignment to defend and attack (as one) rather than depend on holding ground and blocking. Use the power of the body in motion. Defend the centreline with the hand blades.
SAN TAN 三胆
Third, spirit. All techniques and actions taken must be executed boldly with no hesitation. There must be as little "lapse" between decision and action as possible.
SHI RIKI 四力
Forth, technique. All techniques must be simple and pragmatic. Martial arts are not the collection and retention of hundreds of specialised techniques. Rather they are a handful of techniques which "constantly appear" when basic principles are obeyed.
Ichi Gan, Ni Soku, San Tan, Shi Riki 一眼, 二足, 三胆, 四力
First the eyes. Observation is the most important element in initial training. 90% of your progress depends upon your sincerity, commitment and ability to observe.
Do not depend upon your "sensei" he/she is there as "one who has gone before" (sensei) and stands as an example.Through constant observation (ichi gan) and experience as uke (ni soku) body training (actual feel of the technique) you will progress in the art. At a basic level - ichi gan means to "watch like a hawk" and "steal" the technique.
Martial arts cannot be explained by words let alone "taught" by them. They are learned "through the pores of the skin" on the mat during sincere training.