With the astrophysical predictions on stellar evolution (which I admit I am not familiar with in detail) I always ask myself how we can be sure that they are correct although they are extremely simplistic (they have to be, because exactly solving quantum field theoretic problems of the size of a star is outright impossible, even numerically).
Well, for the usual stars, I guess one can at least find retreat in the view that they are all gas or probably kind of a liquid, so they can be justifiably treated thermodynamically, while neglecting as irrelevant some fluid dynamics, boussinesq convection and stuff. But complex stable structure formation within these kinds of matter seems pretty unlikely.
But as soon as it gets to degenerate matter in white dwarfs and neutron stars, as far as I understand it, this gets more and more into the direction of solid state physics. And, if matter forms a lattice of one kind or another, it seems to me more likely that complex structures could possibly emerge, that cannot be foreseen in a (more or less) simple thermodynamic calculation.
As an analogy, imagine a hypothetical astrophysicist from the Alpha Centauri system who wants to understand what is going on here on earth. He knows the element composition, the temperature and pressure, and then he starts performing his thermodynamics math. He will probably find out some chemical compounds, but would he ever reach beyond the conclusion that earth is just a big primordial soup? However, we do not even need to take life into account, there is enough interesting chemistry and structure formation going on on planets and moons. Take for example Enceladus or Io, which have surprised astronomers with their structural richness. Even good old plate tectonics is a pretty complex topic.
So, how can we be sure that complex structure formation is not taking place or is irrelevant in neutron stars and white dwarfs, and that it does not influence the prediction of the stellar evolution of these objects?