Hanu, Yes, in this context, it would have to be 'every'. Also, there is a sense of 'discrete' pattern with this example : you don't know whether he always looks miserable but you know for sure that whenever you meet with him then he is sad and depressed. On the contrary, there would be an idea of 'continuous' pattern if you were to say 'Last time we met and spent an evening together, he looked miserable all the time'.
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