From my short experience: Depends on what you mean. Learning how to do it takes some time, but EOF and RSToolkit are not too difficult to understand if you're really into it, and even if they could (are keep being) improved, they do the job nicely. Then it depends, it goes from within an hour if you grab an Ultimate Guitar tab and convert it if you just want something that plays... To 10s of hours if you transcribe the song yourself, do the vocal, lead, rhythm, bass (and potentially others) parts, polish every single detail, fret position, finger position, hand shapes, exact duration, clean preview song, etc...
Again, I'm not a pro, but usually my process is: - Find a good guitar pro file - Use Transcribe! to check measure after measure every part and add the vocals if I need to (and determine the BPM) - Use Audacity to adapt the audio file and create the preview close to what you hear from ODLCs - Use WWise to convert them - Use my custom made tool to create the vocal part using the Guitar Pro file - Check every guitar part to create 1 to 4 guitar tracks that sounds playable - Add Phrases for each of these track - In EOF, sets the fret positions, finger positions, handshapes, and polish the notes duration to make it look like an official DLC- Create the DLC, in RSToolkit - Debug phrase by phrase each track in Rocksmith 2014
