It should be remembered that a lot of stars are bound by gravity. Usually, stars form because of the different elements and energies that can be found in the galaxy. There are some clouds that form under one molecular cloud. This means that these clouds are just bound towards each other.
A lot of the stars that are part of the cluster are almost the same age. It would just depend on the type of cluster if it is globular or galactic. New clusters are usually galactic by nature because the stars are younger. If there would be no clusters then it will be hard for new stars to form. We still need stars at night. They are very beautiful to look at too.