You actually did take in to account the nearness of the year of Jubilee when buying or selling. The Year of Jubilee was more in the realm of property bought and sold between the Jewish people. Specifically that of productive land, family land, and indentured fellow Israelites. What you are looking for is mentioned in the Bible in Leviticus chapter 25.

https://www.biblegateway.com/passage/?search=Leviticus+25&ve...

The responsibility for making a fair purchase/sale was actually on both parties (buyer and seller). This is conjunction with the sale of property actually being considered the right of receiving the profits the sale of the goods the property produced would have prevented pretty much all short term purchasing. A landowner would not give up their land post seeding and prior to harvest because they have already invested in it, and a purchaser is not going to purchase land after a harvest in the year before the Year of Jubilee because there is no way for them to make a profit while still keeping the land.

EDIT: That being said, there isn't really a comparison here because the leaders of the Jewish people would never had made these kind of loans to the general populace and then expect other members general populace to pay for them.

>you can't take into account the nearness of the the jubilee to not make a loan

What's preventing you from getting a huge loan 1 day before the jubilee?

I read my bible as a Christian, so I know what it says. However I'm not immersed in the culture as it actually played out in practice.

From a reading of the law there seems to be nothing, but I suspect there is something I'm missing. I'm not sure if there is something about who/how you can ask for a loan (thus meaning such a loan couldn't be requested just anytime), or if the culture allowed you to refuse to make big loans then even though the law said you couldn't.

And what Jesus said was "Do not hold back from him who would borrow from you". The point of that may well have been the jubilee.

Realistically you wouldn't.