When testing Just19
script I have a test partition for using LiveHDD installs only, and have had up to 12 OS installed. When I have the ISO's they install here in less than 1 minute it seems. When you get thorougly confused it is very easy to delete them one by one as each one is contained in one directory.
I don't stick to the rules, I will install LiveHDD from any of my OS, meaning I will have to manhandle the stanza to the booting directory (part of the fun)
The test partition needs to be an ext3, unless you are really adventurous trying to solve problems.