My best advice is not to get stuck into playing 'stock' runs and licks. Work out something that sounds musicaly interesting when played slow... then practice playing it faster :D
Some guys just play scales up and down with fiddly bits thrown in and no thought to what they are doing other than playing a load of notes in key as fast as they can. Good shred on the other hand should have the same concept as a David Gilmour solo (just played faster) ie thematic progression and a musical story that has a beginning, middle and end.
As far as practicing runs goes, sure they are important as they can link two phrases together really well. The best advice is not to try copying other peoples runs but to come up with as many original patterns as you can, that's how you get a style of your own.
Seriously, if you like 'shred' music, do yourself a huge favour and get "Perpetual Burn" by Jason Becker (Marty Friendman plays some amazing guest solos too) and "Defying Gravity" by Vinnie Moore - listen to how they put solos together from soulful slow sections and dramatic themes to all out crazy runs and arpeggiated sequences. I only started improving after I really started listening closely to great players. I now try to work a solo out in my head before I start playing because if keeps me from playing the same robotic patterns and runs that I used to practice when I started playing. Using this approach, I now find that writing solos takes longer but the little time I get to play is way more productive. Hope that helps!