I did a VDO over the end of the month a year ago in June. Looks like they lied to me - they said since I was a line holder the next month, I was not entitled to the 50% for the flying after the beginning of the month.

If they were wrong both ways at times - meaning sometimes they paid you too much, and sometimes too little, I might believe it is an antiquated pay system. In my 3 years under this "system", I have only been underpaid. It is therefore not the "system", but a different sort for SYSTEM we are dealing with. It is intentional.