Rainwater in the excavation pit - What to do?

Why is this exciting? With sandy soil, for example, this is mandatory...

Hello, I’m playing grave digger and bringing the topic back up.

I read and hear different statements on the subject.

1. Excavation wet -> remove 15cm
2. Letting the excavation dry out is enough
3. Soil is no longer stable after drying and must be removed even after drying
4. Divert rainwater via trench, that’s enough, everything’s fine as long as the rainwater can drain off
5. Rainwater no longer matters once it is gravelled

Now these statements contradict each other for me both in content and logic.

According to my logic, the soil is not getting wet for the first time. It seeps from top to bottom, right?
Even if it is gravelled, the soil underneath gets just as wet as without. So what exactly is the difference here for the eventual load-bearing capacity?

I would be happy if someone could clarify the different statements for a layperson :)

The initial post was about the tarps (films) that were supposed to protect the slope of the excavation pit from being washed out and slipping and were torn away by the storm. I could not establish any connection to the foundation. If it rains into the still virgin excavation pit and the water stands there briefly, I see no problem in that.