If you check the numbers you found the HOLs between you will probably find them to be 250-251 or 750-751. This is not a ramdom placing. The fives are being cut up in stacks of 250 at a time. Replacement sheets are inserted under the first sheet, along with any inspection sheets, then cut up. You may also find replacements between positions 000-001 and 500-501.
Replacements are still being found in bricks of all other denominations.
Inspection notes are just regular notes out of order and would not have any added value.
Gary