For our SharePoint 2010 Enterprise we h ave a default list view of 10,000 documents. If I create a Parent Folder Called Parent and store nothing in the Parent, but 9,000 documents in a sub folder (underneath Parent) called Child 1 and 9,000 documents in a sub folder called Child 2 would all 9,000 documents be available to view when I click on Child 1 ? Would all 9,000 documents be available to view when I click on Child 2 ?
Not it won't be if you are have default list item threshold value set to 5000 and when you are viewing child 1 view, it will not return data because you have 9000 documents in this folder. Same case goes for child 2 folder.
But Yes..it would be available...provided your item view threshold is set to greater than 9000. This settings you are override for on premises.
Hope this helps..Happy coding..!!!