I've come across the following sentences in one grammar book. I wonder if it's really necessary to use the past perfect continuous in them?
The original sentences:
It had been raining for several days before the heat came.
I had been waiting for a bus for 20 minutes before it arrived.
We had been repairing our new flat for about 3 months before we moved.
How long had you been living in London before you moved to Paris?
How long had your grandpa been smoking before he gave up?
How long had he been taking this medicine before he got better?
I think they would be totally fine grammar and understandable if re-written in this way:
It rained for several days before the heat came.
I waited for a bus for 20 minutes before it arrived.
We repaired our new flat for about 3 months before we moved.
How long did you live in London before you moved to Paris?
How long did your grandpa smoke before he gave up?
How long did he take this medicine before he got better?
or
It was raining for several days before the heat came.
I was waiting for a bus for 20 minutes before it arrived.
We were repairing our new flat for about 3 months before we moved.
How long were you living in London before you moved to Paris?
How long was your grandpa smoking before he gave up?
How long was he taking this medicine before he got better?
or
It had been raining for several days when the heat came.
I had been waiting for a bus for 20 minutes when it arrived.
We had been repairing our new flat for about 3 months when we moved.
How long had you been living in London when you moved to Paris?
How long had your grandpa been smoking when he gave up?
How long had he been taking this medicine when he got better?
How do average native speakers really speak in general?