The answer is yes and no. It really depends.
When you have a muscle imbalance problem, the first order of action is to fix it. This is done using a series of exercises that strengthen the muscles that are too weak and stretch out the muscles that are too tight. The really good exercises work a charm at doing both (for more detailed info, you can read The Whole Story).
Once your muscles are in the right balance using the specific physio exercises, then you can move on to doing more normal physical activities – for me swimming and yoga right now – and those muscles that are now strong get even stronger. In many cases you don't need to do certain physio exercises because they have just become too easy – you are essentially too strong to do them anymore.
I was talking to someone I know about this and she challenged me, saying that she could do her physio exercises until the cows come home but because she sits at a desk all day it undoes all the effort.
Sitting at a desk is bad for your posture. In fact, it's what did me in in the first place. However, now that my muscles are in the right balance, I can pretty much sit at my desk 9 to 5 ish with the correct posture. When you are strong enough, your posture cannot be thrown, unless certain things happen, and this is where the 'it depends' comes into the equation. If you are extremely stressed or working super long hours, then you might not be able to sit up straight. You might find your shoulders creeping up around your ears as you rush to finish that report that is due. Or your back hunching over in exhaustion. Because, after all, your body is not a machine. During times like these, I do need to do my physio exercises to stretch myself out again.
But, over time, I will gradually reduce the frequency of my exercises. I will probably always check that I can do certain exercises required for strength. And I may need to do some of my neck exercises on days where things are stressy at work or if I have a cold, which tends to tighten up your neck because your glands get swollen (I bet you didn't know that!).
If your physio is a good one, they should correct the problem for the long run. And give you the tools to keep the body a well-oiled machine when activity spikes for whatever reason – perhaps stress that's out of your control or even learning a new type of exercise. As much as I love having the excuse to watch whatever I want on TV while I run through my basic set of exercises, I am now testing my ability to go for a short period of time without doing them. First every other day, then every three days and so on. Everyone's body is truly different, so I may need to do them once a week or I may only have to do them once a month. Or perhaps I will prefer to keep doing a few each day, just because I won't have to ever worry about being stiff even if I get stressed and busy. Figuring out what is right for my body (and mind) is truly the next challenge in my rehabilitation process.
So as for most things in life, it all depends. But at least I am safe in the knowledge that I have fixed my posture for the long-run, which is a big relief considering that life can really throw anything our way.