When I worked, in the dim and distant past, we introduced flexitime. The deal being you could carry forward 15 hours (2 days) in every 4 week period. Any balance greater than 15 hours was adjusted down to 15 hours. In the first 4 week period I had a balance of 19 hours which was adjusted down to the 15 hours for the next period where I could claim two extra days leave. Aye, right. As a manager I regularly carried over 25 to 30 hours per period and lost the balance. Did I ever get flexi-leave? No, but the staff regularly brought in their leave sheet to get their 2 days off, month in - month out. I eventually stopped using the bloody system and no bugger noticed!