It depends on your work environment. If your boss asks for 40 billable hours a week and you have a family to keep you busy in off hours then there's not much time for writing docs or contributing modules.
Is the same problem that every person working with free software projects faces. Can I contribute more if I'm not being paid to do it?
In the long run you can expect those extra hours contributing to the project to really pay off, because you gain a deeper understanding of where things go, because you meet people that can help you, because people see your contributions and you make connections and a lot of other goodies.
In the long run you can expect those extra hours contributing to the project to really pay off, because you gain a deeper understanding of where things go, because you meet people that can help you, because people see your contributions and you make connections and a lot of other goodies.