In order not to clutter the - scarce - internal memory on my device, I move everything I can to external memory, in my case this is a SD card, and for larger, databases, a USB flash drive.
When my apps have to create a folder for storing app-related data (preferences, databases, calculation results...), they try to create a folder on DirExternal first, and if that should not exist, they revert to creating one on DirInternal.
Regards,