Deeps Recovery has three scan types. A deeper scan takes longer but looks in more places.

Scan	When to use it	Where it looks
Quick	You deleted the file recently	The most common folders
Deep	Quick scan did not find it	Also app caches, thumbnail stores and hidden folders
Full	You need every possible result	Every folder of your storage and SD card

Tips for better results

Choose the right type first: photos, videos, audio or documents each have their own scan.
Allow All files access. Without it, the scan is limited ("Limited scan – grant all files access for a deeper scan").
Start a scan as soon as possible after deleting a file.
Avoid saving new photos or videos before the scan, since new data can overwrite deleted files.
Let the scan finish; results are grouped by folder when it is done.

Files are verified by their binary signature, not just their name, so files without a name or extension can still be found.