Why the same mistakes keep happening
Most jet lag 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.
Jet Lag Recovery Calculator
Booking the critical meeting for day 2 east of home — the clock will not attend.
Treating westward and eastward travel as the same problem; the recovery math differs 40%.
Napping long on arrival day — a 3-hour nap donates the night's sleep pressure to the afternoon.
Light Exposure Schedule
Getting the direction backwards — evening light when you need to advance is jet lag fuel.
Counting indoor light as exposure; 300 lux does nothing against the sun's 50,000.
Wearing sunglasses in your SEEK window and taking them off in the AVOID one — the schedule inverted.
Pre-Flight Shift Planner
Shifting sleep without shifting light — half the signal, half the shift.
Shifting 2+ hours per day to "speed it up" — the clock resists and the week gets worse.
Pre-shifting for a 2-day trip; the disruption costs more than the jet lag it prevents.
Travel Caffeine Timing Calculator
Caffeine after 2 pm local "to make it through" — it makes tomorrow worse at interest.
Doubling doses on arrival day; 400 mg ceilings exist for a reason.
Counting energy drinks as different — 160 mg of caffeine behaves identically regardless of branding.
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.