Throughout this post, my opinion will be mentioned about the different types of bodies and workout schedules, and the simple 15-35 minutes workouts. Firstly, there are some for each muscle in the body. Here are some examples of some for the abs, glute and legs.
As you can see they are simple and very easy to follow. I personally enjoy doing them every once in a while, because it's fun and entertaining. There are some levels that could either be easy for beginners, normal for people who workout regularly, hard for experts, and extreme for athletes. I find these schedules are useful because they could be a way to keep you organized in your schedule. Some people have difficulty in either keeping track of their schedules, or even doing a workout twice. You may sometimes forget what you were planning on doing, so if you organize yourself a nice schedule, and there will be no problem. Also, there are different types of bodies. The 3 main types are, ectomorph (very thin and hard to gain weight, fast metabolism) which is me, endomorph (basically the opposite of ectomorph, large and round), and mesomorph (best type, easy gain of muscles, similar to ectomorph with their metabolism).
Adding on, do not forget that you can change your body type, you are never stuck in a particular type. Personally, I find this helpful because when you know what type you are simply by taking a look in the mirror, you will know what you need to improve upon. You will realize that you either need a new meal plan, or to do more cardio, or even simply focus on building muscles depending on your body type. It all starts by getting motivated.
Here is an example of an ectomorph, and his transtition to becaming a mesomorph:
Sources:
http://www.bodybuilding.com/fun/wotw70.htm