If the program is protein shakes, then this is what was agreed to pre-op. At least, I agreed to my post-op program before surgery. Does anyone NOT know what their plan is post-op? Unfortunately, not enough people actually think about and ask detailed questions about their early post-op programs. Like a typical 5 year old I asked "why?" a lot. By time I had surgery, I understood Doc's thinking so I understood how to replace one example of something with a different thing that also satisfies Doc's program.
I think most docs go with protein drinks or liquids because they think it will be easier. It doesn't always turn out this way.
Putting energy into whatever the plan calls for *is* worth the energy.
But, you are right, it is about finding a way that works... WITH the Doc. Which get's us to advocating for ourselves when difficulties arise. Make a plan together, make a plan together for monitoring, make a plan together for what happens. When changes are made with the Doc, you are still on program.
Tek