What is a sprint, and how can an overly burdened development team benefit from its execution?

We´re working closely with a company that uses sprints.

Basically, all developers focus on one thing only for several weeks. No involvement in any other business. The good part is that everbody is focusing for a long period of time, and thereby really getting deeply involved in the subject. Therefore, the work is much more efficient than in a "regular" development process, that kind of happens on the side (with regular business and communication going on).

The bad part, obviously: you can´t get in touch in with any of the developers, so if you have an important issue you might still have to wait quite some time, since all resources are tied up in the sprint.