Go back to the 10,000 hours rule proposed by Malcolm Gladwell. If you reached 10,000 hours practicing anything including piano, a foreign language, you would become an expert. Of course you need to have mindful practice, do things correctly and make progress. Repeating hello & good bye in a foreign language day after day wouldn't make you fluent. You need to be adding new words & phrases every week.
Learning a 2 minutes piece in an hour you'd have already run through it at least 10 times and have all the wrong notes fixed. If you repeat the same piece for an hour for the whole week, you'd be able to play it easily but not making more progress.
As you learn more pieces, you learn them faster and vice versa. The faster you learn pieces, the more pieces you can learn. Putting in more hours you're not repeating the same things over & over.