Mostly DailyRest days are part of the plan
Athletes plan rest. Habits deserve the same.
A habit that only works when everything goes right won't last a year. Illness, travel, a busy week at work and holidays are part of every year, and a plan that counts them as failures teaches you to give up.
Rest is not a miss
In Mostly Daily, rest, sick and travel days are real states. They don't help your level and they don't hurt it: the day simply doesn't count as a chance to do the habit. Sick days are unlimited; rest and travel have a soft monthly budget, so rest stays a choice rather than a way out.
Plan time off
Going on holiday? Set time off for all your habits at once. Reminders go quiet, nothing counts as missed, and when you come back you get a calm welcome, not a list of what you didn't do.