There's a bit of myth regarding time management in my view. That said, I think there are two perspectives to the answer - depending on your perspective in asking the question. If you're asking because you seem to be running out of steam before you get the work you need done in a week, I'd suggest your issue is not time management but either energy management or focus.
I've done a few blog/podcasts on this subject from that angle:
On the other hand, if you feel like you work all day and are failing to get ahead on the key and important parts of your day, I'd suggest you have an issue with establishing priorities:
Make it a great day!