[Hadrian (OP)]

If it not broken don’t fix it.

As a physiology outlook to life I wonder if this saying is good or bad as a long term survival plan. What would happen if it was the way nature worked? Would we still be in the soup? In industry how could you survive long tem and still compete against innovation.  Will you end up with a Toyota or British Leyland by following this saying?

[MooseHole]

I think the saying is correct, it just needs to be fixed up a bit.  For instance, you could say that if your product will be surpassed by a competitor soon, it is broken.  Therefore, you should improve (fix) your product.  I'm no biologist, but like if your liver is going to die in 3 years from eating too much butter, it's broken, so you should take steps to fix that one too.

The real spirit of the saying is that if it doesn't matter whether it's improved or not, and it's not really malfunctioning, there's no point in messing with it.  Mostly because it costs resources (time, money, pain) to fix things, and it could potentially cause more problems if fixed incorrectly.

[Ophiolite]

Like all cliches its value lies in its use as a guideline, not a rigid, inflexible rule.

One of the most important, implicit caveats, is that the 'it' in question is the operating, fully functioning system upon which results/product/service are dependent. It is not any experimental replacement system that may be developed in parallel with, but off-line from the functioning system. Thus adhering to the principle in no way inhibits the application of innovation, it merely ensures that such innovation is fully tested, assessed and validated before it is put into functional operation, and possibly eventually replaces the current prime system.

As is often the case the true wisdom lies in knowing when and how to apply the guideline, not in the saying itself.