I know that we use past simple for repeated actions for instance: 'when I was little I went to that school' or 'I worked in that firm for three years' and saying 'I was working in that firm for three years' when I just want to state a fact. Is that wrong or not?
I also know that saying 'when I was working she came to me', this past continuous is justified because it creates the background. What about 'when I was working for three years she came to me'. Is using past continuous here justified too for background information?