Why the same mistakes keep happening
Most global meeting times errors are not arithmetic errors — they are assumption errors. The formula is right, but the input is idealized: a round number, an optimistic rate, a best-case month. Below are the mistakes behind most bad results, grouped by the calculator where they bite.
Time Zone Converter
Fixing recurring meetings in local offsets across DST-switching continents.
Converting once and assuming it holds year-round — DST moves the gap twice a year.
Scheduling the same inconvenient slot every time; the fairness tax compounds into resentment.
Working-Hours Overlap Finder
Locking a no-overlap meeting to one side's convenience permanently.
Forgetting that the overlap window shifts with DST on one continent but not the other.
Scheduling 90 minutes inside a 60-minute window and calling the spillover flexibility.
Meeting Fairness Calculator
Treating "same time every week" as fairness — it is convenience for whoever it fits.
Rotating without telling anyone; the rotation needs a pattern visible in the calendar.
Keeping high-cadence sync meetings when async would carry them — the fairest meeting is the one that does not happen.
Standup Time Scheduler
Fixing the standup to headquarters' 9 am and letting the map decide who suffers.
Rotating without a visible pattern; rotation lives in the recurring calendar entries.
Running daily video standups across 10+ hours of spread — the written format exists for exactly this map.
The habit that fixes all of them
Write down the assumption you are least sure about every time you run a number. If the answer matters, test it: change that one input by ±20% and see whether the decision flips. If it flips, the assumption — not the math — is your real problem, and it deserves the research time.