It is said that originally [in place of the 'Quick-Fix' initiation set we are familiar with in the Takata Lineage], Usui Sensei utilised an open-ended, accumulative process of empowerment/attunement known as Reiju.
[Reiju implies: 'to confer/receive a Spiritual Gift']
Apparently, students would attend training meetings on a regular basis, and at the end of every meeting, during a meditation session, would receive reiju to further deepen and strengthen their connection, and develop the quality of their experience of the phenomenon that is Reiki.
For those who are interested, I have uploaded a full description of a version of the reiju empowerment process at the following URL:
http://www.geocities.com/fascin8or/reiki_reiju.html
'Shikin Haramitsu Daikomyo'
James