Rest is always needed or else you'll get injured just like I did a few weeks back. For about 6 months I had a 6 day workout week, (including working fulltime) and around the 5th month I decided to increase my cardio by tacking on more running. I ended up getting inflammation in my knees forcing me to rest for about 3 weeks. And for those 3 weeks I was crying to get back into the gym. It was a hugh mental setback not being able to do anything til I was fully rested.
Everyone here will agree, rest is as important as the workouts you do. A full day of rest is the best. You wont
build muscle if you dont rest. Here are some ideas to try:
1. Workout different muscle groups on different days (seems like your doing that), but add a full day or two of rest during the week.
2. Someone recommeded this to me, 4 weeks of your regular schedule then 1 week of light workouts then back to 4 weeks etc...
3. Take holidays and special occassion days off. In the beginning I didnt, but now I do.
trust me, in the beginning you can easily get very excited at the gym and excited with your progress which can get you accelerating your pace too soon. At a pace like that you are bound to get injured, which sucks even more than little progress.
again above all remember to stretch for about 5 mins before your workout, and drink tons of water (at least a gallon a day). Whether your trying to lose weight, build muscle, tone, get in shape, those things are essential.