From an unpublished (in English) interview with Yoshio Kuroiwa, who started training at hombu dojo in 1954 and was one of the strongest practitioners in the hombu of the 50's and 60's:
Q: Did you see the Founder at practice?
A: About once a month. He spent most of the time in Iwama, and would just show up unexpectedly at times. He'd appear suddenly, show about two techniques, and then disappear into the back. He would not give us any oral instruction. He'd say "If I show a technique twice it will be stolen", and only show each technique one time. He often said "Technique is not something you are taught, it is something you steal". It was really a kind of contradictory behavior. Anyway, at one time you'd just see him for about 10 minutes.