I use Returnil in safe mode to use freeware that I use occasionally but do not want to install permanently, thus keeping my registry simple. For example I sometimes need to use Format Factory for converting media files from one format to another. Instead of installing it permanently, I install & run it, convert the media format, and save it on a partition other than C: (system partition). Once I reboot, it is as if Format Factory was never installed. However the changed media format is saved on my other partition. Of course this only works if the PC does not require a reboot.