My reorder buffer went from 7 days to 12

I track calendar and business days separately. My quoted ship window was optimistic by ~1.5 business days; once I added a 2-day fudge factor, my buffer stopped yo-yoing. I also keep a 3-day untouched reserve and don't count a delivery as covered until it's in hand and temp-ok. That turned my cost/day from a wild range into a tight band—shipping timing was most of it. Do you log weekends/holidays differently? And are you amortizing shipping into cost/day or just the product? I found the latter hides the real swing.

The 12-day buffer is smart. I added two columns to my own messy note: “days until I first thought about reordering” and “days until I actually did it.” The first was always 3–5 days earlier, which explained why I kept squeaking by. Now I set a calendar alert for day 9, not day 12, because I know I’ll snooze it twice. Also started noting travel weeks separately—those are the ones where my normal routine completely eats the buffer. Not glamorous, but it’s stopped the panic. What made you land on 12 instead of 10 or 14?

Honestly, i do something similar but split the shipping timeline into “label created” vs “first carrier scan.” That gap caused almost all my weird 4–6 day slips, not the quoted window. If first scan takes over 48 hours, I add 3 days to my buffer. I also jot down if I was traveling or extra busy that week, because my “days covered” number gets messy when my routine shifts. Curious—do you count arrival day as day 0 or day 1? That one choice changed my math by a full day and made my old buffer look way off.

Three years in, I finally stopped trusting the vendor's "shipped" email. I log label-created vs actual first scan vs delivery, then set my reorder trigger off the worst scan-to-door time I've seen, not the average. My buffer went from 9 to 14 mostly from that one fix. Also I count a new box as usable only once it's in my fridge/calendar, not when it's "arriving tomorrow." Do you separate label-created from carrier scan? That was the hidden variable in my own note for the first year—there was an old thread about holiday hubs that nailed it.