When I was in school 'we were (always) meeting together'.
Is the sentence in bold an idiom because it indicates the past continuous tense and is not the correct way to say? We can also say it as 'we used to meet'.
So if one used to do something in the past then we can used past continuous form to say that, like 'he was playing football',but it sounds like one is currently doing something in the past like 'he is playing football' in the present continuous shows he is playing football at the moment.
Andrea's always losing her keys.
"In this sentence, the use of always, normally associated by virtue of its meaning with the unmarked tense seems at first sight illogical. However, as we have seen elsewhere, the use of the Durative (progressive/continuous) Aspect with a short action stresses the repetition of that action. The combination of the Durative Aspect and always tells us that this is a an situation that actualises repeatedly, but because the duration of the whole series of losing is limited, it is not presented as a permanent state of affairs
This combination is associated by some writers with some idea of the speaker's emotional attitude, but this will be made explicit not just by the words, but by the whole context of situation and the speaker's tone. It is not true to suggest that it always expresses the speaker's irritation; with change of tone of voice and facial expression, the person uttering the words above could express irritation, resignation, amusement or a number of other feelings. Here, as is almost always the case in English, it is context and other factors that express feelings, not simply the words. The combination can just as easily be used to express pleasure, as in:
He's always buying me flowers.
So, in 'When I was in school we were (always) meeting together', the progressive (continuous, durative) form simply emphasises the repetition of that action. We could express a similar idea with 'we used to meet together all the time'.