Would it really be "conversion" or "extraction" that was measured in the BYO testing. Its probably possible to accomplish either one without fully completing the other. I rarely perform an Iodine starch conversion test, but I always monitor my extraction gravity during each mash.
I probably should check conversion. But as Malzig mentioned from the BYO testing, it appears more likely that you will achieve your conversion if the mash period is long enough to show that the gravity has stabilized. Of course, this all goes out the window if the mash didn't have enough diastatic power or the mashing temperature(s) where incorrect or out of range.