Training plans - how to "extend a training phase"?

I’ve just started a Traditional Base Mid Volume I training plan.
As I read through the Volume I / II / III descriptions, they all have the statement " Intermediate riders along with ultra-endurance riders and riders recovering from injury should consider extending this phase by an extra 2 weeks for a total of 6 weeks."
How does one go about EXTENDING the training plan another couple of weeks? Do you just add similar workouts for longer durations or something? Isn’t that what the next higher phase does?
Meaning, after Volume I is finished, Volume II picks up and increases the workout durations.

Any help or advice appreciated. I’m not actually sure that I would want to extend the plan, but if I decided to would like to understand the approach better.

Thanks in advance.

One way could be to do something like:
week 1, week 2, week 4, week 2, week 3, week 4. It keeps progression but also builds in some more recovery.


Sorry for the late response.
That makes sense… I’ll see how I feel towards the end of week 2 and decide if that’s what I want to do.