That question was mine (for all those stalkers wanting to know my real life identity).

I asked something along the lines of:
"In previous seasons we have noticed from the stands what appeared to be a lack of a Plan B. This has clearly changed this season. Is that because you give the players a Plan B as well as a Plan A? Or because you are coaching the players to be better at making decisions on the fly?"

The answer included points such as:
1. Plan A was provided in the form of "most likely scenarios that would be encountered, and how to deal with them". So not defined, but directed.
2. There was no Plan B.
3. Players were encouraged, and trained to "find a way" (as Chipstead Quin mentioned). This included Gustard throwing possible scenarios from the forthcoming game(s) into the prior training sessions, and trying to keep the players on their toes (also tied into "keeping it fresh"; another key theme of his coaching mindset. See below).
4. The coaches do analyse the threats they are likely to encounter from the next game, and do focus on those. For example talking about how Worcester slowed the ball down illegally at the breakdown, and how to counter that. So this is not a set in stone approach, but a flexible one.

So in answer to my original question, still no Plan B, but also, not quite free reign - more a delicate balance between the two. The solution was clearly well thought through, and a deliberate technique. From my seat in the South Stand, it appears to be working!

Regarding the "Keeping it Fresh" principle, Gustard mentioned that it was important that the players did not get a chance to feel like they were going through the same old stuff every day. To avoid this, they train on different fields, in different locations, mix up the times of training, the overall feel of training, the location and setup of meetings (stand-up, walk-through, etc...). They also get a week off each, the opportunity to have days off for life events, flexibility where needed, etc...

Ronan O'Gara sort of rubbished the idea of a Plan B in his analysis of Ireland's defeat to England. Maybe Plan B is more of a fan thing than a coach thing.