Watch the Mixing Up the Arrangement online guitar lesson by Angus Clark from Focus On: British Metal
This concept works on two levels: Song form arrangement and Guitar part arrangement. These bands created some very versatile long form arrangements ("War Pigs" by Sabbath, "Hallowed be thy Name" by Iron Maiden, etc.) where the song itself changes time signature or feel in a dramatic way. The guitar players in these bands also worked hard to create parts that diversified the sound of the band within more economical song forms.
By diversifying the approach you take to different sections of the song, the more interest you will generate on the part of the listener. Keep your options open and listen for your opportunities to find your space and create the right space for what is going on in the arrangement.