Plan as assembly functionality

We are about to go live with Epicor 9.05 and hope to utilize Plan as Assembly to fine tune our scheduling.  My tests indicate that the lead time has some bearing on whether a job is created for the sub parts or not.  I have yet to figure out the particulars.  With an in-process job and a lead time of 14 days I got a new job to create.  With the same scenerio and a lead time of 4 days I did not get a new job and could use the in-process quantity.

Has any one utlized the "Plan As Assembly" functionality?  It appears to extend assembly quantitiy build requirements based on job assembly quantity requirements and disregards the free and available balance on hand of that assembly.  Is this a correct interpertation?