The recovery week
Three weeks of building, then one easy week. It feels like doing less, but the easy week is where the previous three turn into fitness.
Fitness is built in the rest
Every hard session is a small breakdown; the repair happens afterwards. Stack week on week without a break and the repairs never catch up, so form stalls and niggles creep in. A planned easy week lets your body consolidate the work, and you come back stronger for the next block.
Three on, one easy
A widely used rhythm is three progression weeks followed by one recovery week, sometimes written 3:1. On the easy week the long session drops back to around 62% of the week before, then the climb resumes from where it left off.
It is not lost time. Backing off on schedule, before you are forced to, keeps the whole plan moving. An easy day is training too.
Listen, then adjust
The calendar is a default, not a rule. If life piles up or you feel flat, taking the easy week early is a strength, not a failure. TrailFree replans around what you did, without blame.