No less time consuming, in terms of teacher-student direct contact, than precisely transmitting 118+ paired kata?
You actually believe he was involved in "precisely" transmitting 118+ paired kata?
When he asked Shirata not to leave, but stay and help his son-why do you think Shirata chose to teach Solo training as "The fix?"
Why do you suppose Kisshomaru banned them in favor of paired waza?
Why do you suppose Kisshomaru never had his fathers power?