There are patterns to it, because the neck is just a series of patterns. Do a YouTube search on finding octaves. So "2 and 2" on the 6th string will take you to the same note, different octave. 

Example:

3rd fret on 6th string is a G.

Go down 2 frets to the 5th fret then over 2 strings to the 4th string and you have a G note just a different octave.

But once you know the pattern there is no escaping practice. It's a tough instrument to learn.