why imperfect in "no aguantaba más de diez minutos"?

Question

I got this sentence out of the dictionary, but I wondered about the tense...

no aguantaba más de diez minutos

she couldn´t keep it up for more than 10 minutes

Since there is a specific period of time mentioned, why should it use the imperfect tense?

Answer 1

Since there is a specific period of time mentioned, why should it use the imperfect tense?

Because imperfect tense can be used (and are often used) when no periods of time are mentioned?

No aguantó más de 10 minutes - At that/those specific times he could not stand much longer, and that's it, finished action

No aguantó más de 10 minutes - At any unspecified time/times he couldn't stand much longer. We don't know whether it kept happening or not.

Answer 2

The couldn't (this time) part expresses the doubt of duration and implies repetitiveness. This particular time she couldn't keep it up more than ten minutes. Next time who knows? A new Olympic champion.

Answer 3

I could be wrong, but I'm reading like this (let's remove the negative and the más to simplify it)...

Aguantaba diez minutos = She was enduring for 10 minutes (bad English, but maybe it will help to see how the Spanish is viewing the situation).

That is, it was something she was doing for a time (as opposed to a one-off event). English still sees it as "endured," of course.

And, please don't take this as authoritative. Spanish frequently puzzles me with tenses. I'm not saying this is how or why, only that this is how it is making sense to me at this time.