Before anyone thinks I am focusing on Saotome, let me just make clear that all of the "uchi-deshi" (kayoi-deshi?) in Hombu from about 1955 to 1969 got far less hands-on time with Morihei that aikidoka in the West would expect from the term "live-in disciple." And the Japanese who stayed in Japan like S Endo are quite frank that they didn't train all that much with Morihei. Their major influences were men like Tohei and K Osawa. They took uke for him a few times, heated his bathwater, etc. But Saotome's and Endo's value to us today has nothing to do with how much hands-on time they spent with Morihei. Its only in the West where people take this "I trained daily with the Founder" material seriously.
I will check the unedited notes from Imaizumi Sensei's Aikido Journal interviews, but my recollection is that the uchi-deshi system was ended in 1964 and changed so that those students became known as shidoin (junior instructors). Just another fly for the ointment