Vary your routine! Speed like that is good to have, but should not be the only thing you practice. Try practicing with a drum machine or metronome, and focus on playing
r e a l l y s l o w but try to get perfect timing down. That will take the strain off your hands, wrists and forearms, and put it on your brain where it belongs. Your brain can handle it, no problem.
Gradually speed things up (like over two-three weeks) and when you've got it down, your speed will count for something, as you won't be just fast, you'll be fast *and* good.
Kinda like a gunfighter focusing on accuracy, versus just the quick draw. A quick draw without accuracy will leave you dead in the street.
As for perfect timing and what it is - depends on the style of playing, but above all it should be consistent - some styles have the bass hitting the beat just slightly after the drum, and some styles have the bass hitting the beat just slightly before the drum, and many styles have the bass and drum hitting the beat in perfect synch. Try all three until you master them all! Start with synching with the drums first of course.
Also practice improvising - pick any song, download the lyrics and chords (I don't mean tabs), and without listening to the song at the same time, emphasizing the chord tones from all the scales you've memorized, try making up a bass line to those chords. Then try it with the song playing also, and focus on playing your own thing, not what the recorded bass player is playing. This will teach you how to add your own substance to a song, make it your own, and how to complement the melody and guitars (or other accomp. instruments, like piano, whatever style you listen to). I'm assuming you play metal, but maybe I'm wrong.
You can also train your ear - take some songs that you don't know all that well, maybe even a style you're unfamiliar with, even something crazy like country or pop, and try to learn the recorded bass player's part by ear. Start with something easy (like a simple country tune) or something repetitive (like a pop song or a funk or Motown song). "I Was Made To Love Her" by Stevie Wonder is a great example of a very repetitive bass line that just friggin' grooves! Then when you've got it figured out, write down your tab or notation, and see if you can figure out what the chord changes are. Then download the chords for that tune also, and see if you're right (or maybe the ones you download are wrong!).
These are the sorts of things that will make you a better musician and ensure you will have fun playing for the rest of your life, no matter what style you play!
Speed is nice, but without the foundations down, it is useless and meaningless, and will only wear you out.
Can you practice to much??? 
