Personal blog on early retirement and analytics projects. I write about what I learn as I am learning it.
The 4 on 4 off schedule is the easiest rotating shift pattern there is to explain to a new hire: work four consecutive shifts, then get four consecutive days off, on an 8-day cycle that just keeps repeating. No block-counting, no mid-cycle exception, nothing to memorize. The trade-off is what it does to the calendar — and that trade-off is the part most explanations of this pattern skip.
If you searched for a rota planner rather than a “scheduler,” you’re probably in the UK, Ireland, Australia, or New Zealand — Commonwealth English keeps “rota” and “roster” for the same thing American software calls a schedule. The vocabulary is different; the underlying problem, for a 24/7 team, is identical: cover every shift, honour rest between shifts, and don’t leave one person doing all the nights. This is a free rota planner built around a real solver rather than a grid you fill in by hand, and it makes no assumption about which side of the Atlantic you’re on.
Most security guard scheduling software is built for a company running dozens of sites and dozens of guards, and it prices itself accordingly. A single post that just needs to be covered 24 hours a day with a small team doesn’t need any of that — it needs a rest rule, a rule against a day shift the morning after a night, and someone to spread the weekends around fairly. This is a free tool built for exactly that smaller, sharper version of the 24/7 problem, with a solver underneath it instead of a template.
Search for nurse scheduling software and most of what comes up wants a signup and a credit card before it shows you anything. This one doesn’t, and it’s built for the part of nurse rostering that actually breaks ordinary scheduling tools: a ward runs 24 hours a day, so the rest rule, the consecutive-nights cap, and the no-day-after-a-night rule all have to reach across midnight — a boundary a day-by-day template has no way to see at all.
Construction schedule delay analysis almost always starts from the same document: the float table. Which activities had slack, how much, and therefore who owes whom the days. It is the number that decides whether a delay was excusable, concurrent, or somebody’s fault, and it is on the front page of every claim I have ever read.
So I tested it. I took a 21-task renovation with three general crew, delayed every single task a day at a time, and re-solved the whole schedule after each one to see when the finish date actually moved. Twenty-one tasks, a few hundred solves. Three of them turned out to have nine days of float on paper and no tolerance at all.
