Download Package Content - Move instead of Copy and Delete
When utilizing the "Download Package Content" TS step and choosing to download to "Configuration Manager client cache", the data is first downloaded to the temporary folder smstasksequence. After that the data is copied to the Client Cache folder (%windir%\ccmcache) and as a last step the data is removed from the smstasksequence folder.
This process means that before the data in _smstasksequence is deleted, 2 copies of all data reside on the disk.
This results in the need for extra free space (2x the data) for the running TS.
A move instead of copy and delete might be a better option.
Micah Taylor commented
Or just download directly to %windir%\ccmcache (or the custom folder) instead of downloading to the _SMSTaskSequence\Packages first and moving or copying from there. This is a big deal wen the package is OS media or a large driver package. Either way having two copies of the package during the task is less than ideal.