Earlier quoted context omitted.
Well except when it doesn't, I guess. All combination of consonants may unpredictably get rounded down to f (wszystko) ą pronunciation at the end of the word has a wide range of sounds depending on regional accents, ę is the same but worse because it's usually ignored even in common words (część), you have all the usual Ci Cy Ca rules for palatal consonant, except these characters can also be part of longer sequences…
I would not be so optimistic to say 99%, but I think a lot of things like that could be actually assigned to some rules that are, well, actually applied pretty consistently. E.g. isn't devoicing of 'w' in 'wszystko' just the case of clusters of voiced and voiceless consonants? Similary 'Hodów' shows devoicing consonants at the end of a word. I'm not sure about 'ą' - some examples would handy, but if we are talking ab…
Ą is a bit more regular at that, so usually loses the n when at the end of a word and never heard without n when in the middle of a word, except in places like Warsaw, and other cities up north, where I was called out as gòralski (which is funny considering I'm Italian, I guess I'm learning polish wrong but convincingly enough)