I am going to sell my phone.
It's a Samsung Galaxy S4 i9505 from Germany running Android 5.0.1 "Lollipop". What I have done so far is to encrypt, reset, run camera until memory was full to override empty memory with random data and then reset again. But I think I have forgot to disable "fast encryption" which encrypts only the used memory (I have manually deleted some files before ). I am not sure if I have disabled it or not.
Is it a good idea to perform the encryption again (with "full encryption"), or is multiple encryption a bad idea in case of security?