When a cycle gets blown up, you replan the remainder rather than abandoning it. Keep the dates, keep the name, move the surviving tasks into the next cycle sheet, and write down what happened. The cycle still ends when it was always going to end. That part is the whole point, and it is the part people give away first.
Before any of the advice, the confession.
The first three cycles were a disaster
We were ready to give up on this idea after the first one. Nothing went according to plan.
The second time we tried, same thing.
The third time was the most frustratingly comical mess of all, made significantly worse by me being the cheerleader going in, saying "c'mon guys, third time's a charm." We were on day two when a project came in and wiped the entire plan out the door. Everything we had worked on was a waste.
But that happens with projects, all the time, all over the world.
Get over it.
I say that bluntly because the alternative is what most teams do, which is decide the method is broken and go back to a calendar full of things nobody planned.
What was actually happening
The whole time we were failing, we were still learning.
Each cycle we took note of what upset us and worked out what to do differently next time. It was like filling the holes in a leaky boat. Every single time we fixed one thing, something else popped up.
That is not the method failing. That is what moving an organization from reactive to proactive actually feels like from the inside. It is unglamorous and it takes about a year, and nobody selling you a framework will tell you that.
Like meditation, this can be practiced and never perfected. Be patient about it, and be persistent.
The four things to do when it happens
Keep the end date
Whatever else you change, do not move the finish line. A cycle whose end date slides is just a project, and projects do not end.
The date is what produces cognitive closure, which is the actual benefit you are buying. Anyone who has run a business knows the feeling of never being done. The date is the cure and it only works if it is real.
Replan the remainder, do not abandon it
If you fall behind, move the task to a different day in the cycle, or look to shorten the amount of work required to complete it. The sheet makes this cheap: you can move something to a different week without messing up anyone's day.
If a task leaves the cycle entirely, delete it from the sheet and write down why. That note matters more than the task did.
Review the notes at the end
Go back through the removed items when the cycle closes. Sometimes you plan for the wrong things and do not realize it until it is too late, and that list is the only evidence of how it happened.
The single most common entry in ours was scoping. We messed up so many cycles by planning to "plan a project" inside a cycle, then discovering we had vastly underestimated the time and effort the project needed. That ruined the meticulous planning around it, upset the team, and made us think cycles were stupid and would never work for us.
The fix was not trying harder. It was asking "and then?" until the task stopped hiding.
Do not cancel the break
This is the one that kills the whole thing, so I want to be unambiguous.
When a cycle goes badly, the instinct is to claw the time back by working through the two weeks off. Do not. The break is what pays for the six weeks, and a team that watches it get cancelled the first time work slips will never believe in it again. You will have taught them that the rest was conditional on everything going well, which means it was never real.
A bad cycle is a reason to plan the next one better. It is not a reason to delete the part that makes people want to do this.
What to say to the team
Say it went badly. Say what you got wrong, specifically, including your part.
I was not a good leader for a long stretch of this. If I was habitually late for every meeting, how could I expect my team to be on time? My own inability to plan and prioritize became my team's inability to plan and prioritize. It is a waterfall effect and it starts at the top.
The Friday check-out is where this conversation belongs, because the format already asks what did not go well and what the group wants to change. A failed cycle is just a bigger version of a question you are already asking every week.
When it is not the cycle's fault
Sometimes a plan breaks because the work genuinely changed. A client emergency, a deal that closed early, a person who left. Those are not planning failures and you should not treat them as ones.
The tell is whether you could have seen it during planning. If the answer is no, replan and move on without the post-mortem. If the answer is yes, that is the note worth writing.
And to be straight about the limits: six-week cycles are not the magical solution your team has been looking for, and I do not think they are the answer for every organization. They are a starting point. A way to open a conversation about whether the people in your company are happy, and honestly, about whether you are.
The whole method is in the guide to running your work in six-week cycles.