is general relativity truly the best model for gravity if it permits singularities to exist? in any other framework, singularities indicate your model is wrong, doesn't it? the notion that there's a singularity in black holes implies indeterminate structure, yet we can't extend past that. is that due to lack of data or reasoning? if so, what happens when discussing density or entropy in that region?

also, when a black hole forms, how long does it take to form? if a bunch of mass collapses within the Schwarzschild radius, does the singularity and horizon just instantly form or is it at the speed of light?