why is it good to do more than one of the same type of excersize during a workout session, like doing bicep dumbell curls and bicep straightbar curls? Dont both of those work the bicep muscle the same exact way?
For what I understand, you try to look for different routines that will work different parts of the body. For example, you mention biceps. The way I do things is that I look at the bicep and see for example that hammer curls work out the outer part of the bicep, while barbell curls (to me the most complete of the bicep routines) works out the whole bicep, except for the outer part of the bicep. Then you have the concentration curls that heavily works the inner part of the bicep (or the part closest to your chest), at least that's what it feels like when I am doing them. You see, the best thing to do is find out what works where and design something based on that. Use the exercises that work the same part when you get bored of your current routine and want some VARIETY (as John would write) in your workout. It's good to keep you on your toes.