Process is idiosyncratic. Other students write best under the pressure of a last-minute deadline. All that we can ever judge are their products. Granted, we can and should offer some guidelines on processes. But we shouldn't force all students to follow a set method.
Cognitive styles differ.
A writing process that helps one student might totally hamstring a second. Granted also, we can and should examine the product at varying stages of drafts and revisions. How those words reached the paper may be an interesting puzzle for the psychologist. But it is inherently beyond the direct influence of the composition instructor. Someday, of course, the composing process may become an open book.