It would be more accurate for the 'days cover' feture to be taken from the 90 days sales over the 30 days sales to even out large peaks or troughs.

The information would allow a far more accurate look at how an item sells and how best to order.

Additionally the sales and replenishment report could also have the date of the next PO arrival. At a glance we could then assess the sell rate, the stock that is left, and whether it will last untl the next delivery or if an adjustment to speed up or slow down sales needs to be made.