Why are You Supposed to do Strengthening (Reps and weights and stuff) Every Other day?

People say that you are supposed to do strengthening every other day. That you do your reps one day and than take the next day off and than do the reps and weights and stuff again the next day. It's about your muscle breaking down and stuff like that. But does it help you build muscle faster than if you do it everyday? And does it help you get toned more quickly if you do it every other day. I do walking and stuff everyday. I walk about 2-3 miles everyday or more and sometimes do dancing or a bit of jogging or biking. I know that burns fat. But in magazines and stuff they have these articles on exercise programs. They give you some strengthening exercises (Crunches, and ect.) and tell you to do them every other day. Will you get more results by doing it every other day or everyday?

If I'm confusing you here's my Q in short form:
*Why do people say to do strengthening every other day? What does it do?
*Will I get better results by doing it every other day or everyday?
*How fast do you build muscle?
*Do those strengthening exercises actually work and tone your body. If I also do exercises like walking and dancing and stuff everyday?
*If you're not overweight and have just a bit of fat on your stomach and legs and arms (But are not overweight) how fast on average does it take to start seeing results? You have a pretty much flat stomach but not perfectly flat.

You are supposed to strength train every other day because it gives your muscles a chance to recover. When you lift weights, your muscles incur tiny little tears, and as those tears repair, your muscles get stronger and bigger. They 24 hours to repair. That's why you take a day off. If you are lifting heavy weights, you will get better results doing it every other day. If you are lifting light weights, like two or three pounds, you can do it every day because all you're doing is stretching and toning anyway.

Building noticeable muscle takes about six weeks.

Strengthening exercises do tone, but doing all different kinds of exercises gives you the opportunity to use many muscle groups and enhance your results and your fitness.

If you have just a little bit of fat and you exercise consistently, you should expect noticeable results in two weeks. You will have dramatic results in six weeks.

The idea behind lifting every other day is to give the muscles a chance to repair themselves. You can lift everyday as long as you are doing a different body part. This may hold true in some cases but if you look into I am not truly sure that this holds up. There are some very physical jobs that are repetitive and have to be done all day long and everyday. These jobs build strength and they don't take off every other day. In rehabilitation you exercise the same muscle group once or twice a day five to six days a week. To me it is not so much the muscles as it is the joints. As one ages there is an accumulative damage that has occurred and by giving the joints a day to rest it saves wear and tear on them. Look at professional bikers who ride a hundred or so miles per day taxing the muscles to unbelievable levels and this is done day after day. Again it is more of what we have become accustomed to than anything else. One doesn't have to lift heavy to gain good size. Technique is everything. Lifting has a side bonus in that it consumes calories long after the exercise is over. That should help you loss the extra weight that you are carrying. To gain a flat stomach one has to watch what they eat more than the exercises done.