No one knows. But academic management literature doesn’t lack for models, theories and research.
“The conventional argument, primarily drawn from upper echelons theory, is that long-tenured executives are a source of organizational complacency. That is, they tend to resist change and embrace the strategic status quo.” Despite this summary statement in the Acad. Mgt. Rev., Feb. 2005 at 71 (citations omitted), the authors suggest at least one counter-explanation. Long-tenured general counsel, to stick with our domain, may not resist change per se, but rather, that they tend to be found in firms with good performance, where a change in strategy may simply not be warranted.”
From a different perspective, you have stayed for many years because you have done a good job and the company has prospered, so why change a winning game?