When the 4th and 7th intervals are incorporated in the 5 Pentatonic shapes, it offers the 2 extra positions needed to make the 7 Modes.
Learning the patterns of all modes allows you to see how the patterns share with each other from Major scales, minor scales, Pentatonic scales and the Modes.
Example; Take the interval pattern of the B Phrygian mode starting on the 6th string, 7th fret and follow thru on all strings.
Continue using the Phrygian pattern that takes place on the 5th string, 7th fret, only this time starting it from the 5th string, 7th fret (The E Note) and continue the same interval pattern down the strings. This is the E Aeolian mode. All of the patterns relate to each other when started from a different note in the Key.
Knowing the interval function of each mode gives you the ability to understand how the structure works, especially when using them in Parallel form.