Necroing this thread simply because it ranks high in Google results so I assume it's still getting lots of traffic.
It's worth noting this specific text from the Lyre of Building's description: "Each hour after the first, a character playing the lyre must make a DC 18 Perform (string instruments) check. If it fails, she must stop and cannot play the lyre again for this purpose until a week has passed."
Based on that, only if the perform check fails is the user restricted from playing again for a week. It appears perfectly legal for someone to play the lyre for eight or so hours every day for consecutive days provided that they don't fail a perform check.
