There is a pattern to the plans. I choose a plan start date that assures my social runs are on foundation days so I have some flexibility. If I need to start early, continue a bit more, or bail early, for social days I adjust.
Endurance runs can be a bit tricky. They are preceded by, and followed by, an easy day and slipping a day can cascade into the next week. I try to keep Saturday sacred for my endurance run and reserve Sunday for a recovery day that I can run socially or rest.
The coaches can better suggest a fix when you need to move the long run.