Agreed. I was thinking of police interrogationsI think that the word order will depend on the context rather than which appears more frequently.
A: What were you doing yesterday evening?
B: I was watching TV.
A: "What time was that?"
B: "Seven o'clock."
A: "What were you doing yesterday evening at 6 o'clock?" - the emphasis contrasts with "seven o'clock."
A: "What were you doing at 6 o'clock yesterday evening?" - This is a precise question.
I suspect that it is. It is a useful form of the verb as (i) it gives an immediacy to the words spoken (ii) it allows a second action to take place at the same time, e.g. "I was watching the TV when he came in."the past continuous is more common in Spoken English, isn't it ?