It could be 2 or 3 songs off of each album. Doesn’t have to be the whole thing at one time.
A lot of metal artists have a classical background. If you really want to hear some wild stuff, try Judas Priest. They have two guitarists, K.K. Downing and Glen Tipton. One is trained in Classical and the other in Blues.
I think the Holy Grail piece I heard was My Last Attack. Just caught a You Tube of the Released Version, but what I heard went on, it seemed, a whole heck of a lot longer than 6 minutes.
When I heard that poll about the songs the soldiers liked going into battle, I always thought Hendrix All Along the Watch Tower would do it for me. Probably dates me a bit. :)
Up the irons!