I was reading a sentence from a friend about apartments:
Mein Bruder hat lange Zeit in einer Mietwohnung gelebt.
Now, translating this to myself I thought this meant
My brother has lived a long time in a rented apartment.
But, I thought as Zeit is a noun in this sentence, I would need the indefinite article "eine" i.e.
Mein Bruder hat eine lange Zeit in einer Mietwohnung gelebt.
Both variants are possible. The one without the indefinite article sounds more natural. Some people may even think of the number word ein if you used the indefinite article in this way, and ask if you specificially meant one, not two or more.
Das hat mich große Mühe gekostet.
Das hat mich eine große Mühe gekostet.
If you want to make sense of it, as a rule of thumb a noun shouldn't be lonely in German but three are one too much. This is more a stylistic than a grammar rule, of course.
