A 6-month rule of thumb is a tax on your working capital.
Holding 6 months of cover for an A-item with steady demand is statistically wasteful — that's a 95th-percentile-plus stockout rule applied to SKUs that only need 30–60 days. The cash gap is real, and it compounds across every reorder cycle.
Trailing averages miss seasonality and trend.
A 6-month moving average is half-blind on every Q4 ramp. skubase fits a Holt double-exponential model with a weekly seasonality factor, so a back-to-school SKU isn't reordered like a steady-state one.
All SKUs are not equal.
Your A-items deserve a 99% service level; your C-items don't. skubase segments by ABC × XYZ and sets safety stock per class — the math the spreadsheet can't do without becoming a part-time job.
Your suppliers are unmeasured.
If your spreadsheet doesn't track which vendors miss promised lead times, you're carrying their failures as your stockouts. skubase scores every vendor on on-time, fill rate, and lead-time stability.
Dead stock is a cash recovery problem your sheet ignores.
The Sheet shows you what you have. It does not propose a markdown plan, a bundle, a wholesale list, or a write-off. skubase does — with the dollar impact attached.