We do offer more ways to recover deleted data. The first one is recovering the data from SQLite databases, the second one is recovering the files and folders from Physical images.
SQL databases allow you to recover the data which were marked as deleted or are still present in a database folder. SQLite is the most common way to store data for both iPhone and Android.
Physical images allow you to recover deleted folders and files which are still available through the file system, plus the SQL databases as well, which makes it the best option to obtain the lost data.
With Rooted/jailbroken devices we are able to get straight to the file system and SQL databases as well.
Devices without the root or jailbreak are the hardest ones to recover, yet there is still a chance to obtain some of the data although it will be significantly less than the options above (or none).
Velocity also plays a big role in data recovery - the longer you wait, the lesser are the chances for successful operation. Restarting the device (or even apps) might increase the risk of permanent loss of your deleted data as well.
It is never 100% guaranteed you will be able to retrieve deleted data. The amount of recovered deleted data depends on various factors such as how long is it since the data was deleted (30 days at most), was it a factory reset or not and such.