I was a long time knocking at Ruth's door

[Glizdka]

In Cambridge English First Handbook for teachers for exams from 2016, I found a sentence that I've never seen or heard. I'd like to ask if it's natural.

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TASK 28, PAGE 16

Complete the second sentence so that it has it has a similar meaning to the first sentence, using the word given.

I knocked for ages at Ruth's door but I got no reply.
LONG
I _____________ knocking at Ruth's door but I got no reply.

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ANSWER KEY, PAGE 20

spent/took/was | a long time

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Does this mean that "I was a long time knocking at Ruth's door but I got no reply." is a valid answer? I've never heard or seen anything like it.

 

[emsr2d2]

It's grammatically correct but not common. The only phrase in common use that uses it is "You're a long time dead".

 

[Glizdka]

The only phrase in common use that uses it is "You're a long time dead".

Is this similar to "you only live once"?