When you hover on a completed step you see a "repeat" icon appear. If you click it, you uncheck the step. This means that you can go back in the process and do a rework.
Maybe a new design or website copy didn't get approved and now based on the feedback, you can rework it. Maybe the report you were writing needs a few more details to be added.
Every time, you have to rework something, you can start an iteration on a step and go through it again. This keeps it visually clear for everyone on the team where are we at and you won't be getting questions and pings about that.
Great work doesn't happen over once. With feedback from the team and the newly obtained knowledge you can keep a sense progressing but still make changes that will improve the final results.