When you start a new weight training routine you will usually require about two minutes of rest between exercises.
But as time passes and you get stronger you should gradually reduce the rest period between exercises so that eventually you should be able to go through a full work out with little or no rest between exercises.
Depending on your age and fitness this may require at least two months of really hard training before you can go through a full work out non-stop, moving from one exercise to the next.
But do not rush at when you start because if you do rush, you will be unable to work your muscles as hard as they require to get results.
This brings us to the next time related factor which uses the speed of movement during the exercises.
Some people like to train at a fast as possible movement and others say almost the opposite.
So what is the best speed of movement? Well really nobody knows and that is a fact.
But I personally found as have others that a fairly slow speed of movement produces much better results than a fast speed of movement.
And a fast speed movement can sometimes lead to a jerky movement which can not only can cause injury but it doesn't fully exercise the muscle group in question.
A dangerous yank of a barbell can potentially do a lot of damage such as ripping your biceps muscle.
Yet in practice this is how many people train and wonder why they never produce the results they hope for.
In summary there is no right or wrong way for the speed of exercise.
But keep in mind the faster the exercise the more chance you can lose control which puts you at a severe risk of injury.