In Windows, there are MSI packages that automatically cache themselves on the local machine. Examples include legacy MS Office applications, Adobe Acrobat, and other such big names. But I find that many lesser known applications do not automatically cache their installation source files on the local machine. This is because the program extracts the MSI to the temp folder where it would later be cleaned up by garbage collection. Or the package simply relies on the same directory from which the MSI was last run. This tends to be an unc path and sometimes, repairs have to be done while the share is unavailable. Either way, it makes alterations and repairs to installations difficult (or impossible) if performed without the original installation package(s).
One way to forcibly cache the source MSI files for such programs is to go into the sourcelist registry key and change the registry values to point to a local directory containing the MSI. While I won’t go into much detail here on how to do this, what I will explain is how to find the correct sourcelist directory for a particular program.