I have never understood why some people think negatively on working with more than one project at the time.
If you ask me, I work better when being involved in several projects at the same time. One reason for that is that I can shift project when I loose inspiration for working on the other.
This way I can keep my interest up for a longer time and by that do more quality work. Another reason is that the different projects are feeding each other with thoughts. If I switch projects, I will still have my perspective from the other project fresh and bring this into the second project.
Take the content in one project out of its structure and put it in the other projects structure and you´ll see that you will be able to come up with more diverse and out of the box ideas. It helps me look at solutions in another way, a little bit like I was schizophrenic. Maybe I am?