 Re: Assimilation of /ʒ/ /dʒ/ and /tʃ/ sounds
No - "endure" could be pronounced either /endjʊə/ or /enʤʊə/ - it's the same rule as in the other examples. Whether the two sounds are in different syllables or the same one is irrelevant. If the two phonemes are adjacent then yod coalescence can occur - as your final example shows.
I'm not sure why you say the /z/ + /j/ can become /ʒ/ change does not happen regularly - I can think of loads of examples. It could happen eg in any of the following :
gives you / John's yoghurt / he's young / was your / goes yearly / does yoga etc etc etc
And don't forget that /s/ +/j/ can also become /ʃ/ - eg :
bless you / nice yacht / pass your / issue / etc |