There is a tendency when thinking of the concept of shu-ha-ri in martial arts to assume that it must be a linear progression that takes places over a set period of time. Chiba-sensei has written
about shu-ha-ri in these terms, stating that shu takes place up to sandan, ha takes places from sandan until godan, and then ri takes places subsequent to godan.
While that is one interpretation of this metaphor, it is not the only possible one. Metaphorical concepts in martial arts only serve to illuminate some aspect of physical training and, while they may be useful in this regard, it is unwise to get too caught up in an attempt to establish an absolute intellectual meaning to such concepts. This is impossible as they have no independent meaning of their own. So while Chiba-sensei$B!G(Bs discussion on shu-ha-ri may be relevant within the context of his specific teachings, it should not be seen dogmatically as the only basis for a more general understanding of the concept within aikido or other martial arts.
Another way to view the metaphor of shu-ha-ri is as a reflection of the natural process of learning and relearning principles and ways of executing techniques that occurs in the study of any martial art. As such, it can be seen as a constant process that has no fixed beginning or end. Students on their first day go through the process as they start with what they think the technique is, then continually break down that understanding and rebuild it until it resembles something that actually works (within the context of efffectiveness that has been defined: sometimes, particularly in aikido, what "works" for a student in the dojo setting is simply making the teacher happy even when doing so requires using movements that would be useless in a real conflict).
Seeing shu-ha-ri only in the context of whether one copies a specific kata or changes it is, to me, a reflection of the overemphasis on form in aikido that has been discussed here earlier. When we are able to break out of seeing the art only through the lens of form, which may be a completely different process from shu-ha-ri or which may be a manifestation of that process for the art as a whole rather than for each individual in the art, then we see that the forms themselves are not the art. Rather, it is the principles they manifest, and the ability to apply them, that constitute aikido (and all other arts).
Such principles are not only expressed through forms but through all movement, and hence the validity or correctness of those principles can be addressed whether they are expressed through form or non-form. In such a view, shu-ha-ri can be seen as not relevant to form at all but as a reflection of the development and evolution of the principles and patterns of movement that constitute what we would call a $B!H(Bstyle.$B!I(B