Are all installations of OS X (10.8+) Case Insensitive (by default)? I'm going to be getting a refurbished machine and rather than keep my current OS (10.6.8), I need to upgrade to at least 10.8, in order to be able to communicate with devices that use iOS 9 (since you need a newer version of iTunes).

My current install is Case-Sensitive and Journalled, and it works well for me.  The issue is, I will also need a newer version of Adobe Acrobat (9 or higher), and everything I've read says it requires a Case-Insensitive file system.

So here's my question: if Acrobat is so popular and often used, does this mean that installations of OS X are by default Case-Insensitive, or does everyone have to reformat and reinstall OX S after the purchase Acrobat?
By default, HFS+ in OS X is case-insensitive. You have to specifically erase a partition and select case-sensitive for a partition to be case-sensitive.

It's not that common, but there is software which requires case-insensitive HFS+. It's more common for legacy software to require case-sensitive HFS+. Of course, software should work on both, and most newer software does. The Acrobat restriction feels like a way to avoid unreproducible bug reports from users using (awkward) case-sensitive volumes.