I think 5 or 6 songs from the new album is pretty good in a Metallica set. They have a lot of material to cover.
Agreed. Also, I think there are only 5 or 6 songs I feel like I'd want to see over older stuff anyway since I've never seen them live.
Right, that's what's tricky about a Metallica set, there are a lot of songs that fans (casual not diehards) kinda expect to hear. Diehards might not want to, but your average concert goer is going to want to hear Seek, Hit, Creeping, Fade, Bells, Master, Battery, One, Sandman, Sad, Unforgiven, NEM, Fuel, etc... That's a bunch of set time right there.
I think they have been doing a good job so far of playing new stuff, live standards, and some other random things as well.