Jay, I assume that your job is solution oriented which means that you are paid for the solution you produce.
There are required resources to develop a solution and I think I should also assume the amount of resources are fixed for you, that means you have certain amount of hours you will dedicate to your work. And you would like to go offline from your work outside that time.
With fixed resources, improvements of efficiency and effectiveness can only be improved by the reallocation of them. I think if you research on ways on reallocating resources will help you out.
Here are something for you in my mind:
1) Knowledge management
Solution is developed heavily based on your knowledge. So knowledge management is probably a good starting point. One focus is on storing knowledge. If you have good amount of knowledge in your solution domain, you are readily prepared for that task and you can spend less time thinking about it.
Another focus can be on knowledge sharing. If you know more people who are willing to share knowledge with you, then you can get more of the required knowledge for your project with their help.
2) Solution reuse
It can be done either reusing your own solutions or open source solutions out there. It is related to KM again because you need to organize your information on solutions in order to retrieve them in a timely manner. :-)
3) Delegate tasks that are not in your strength
Focus on your strength and delegate when it can be done just as good by someone else. This way, you can maximize your productivity because you are really focusing on the things that will bring you highest return. Making connection is quite important. :-)
4) Measuring and planning your project
I assume that your work is achievable in the time given to you, so that you need to measure and plan on how you are going to deliver your solution. The big three elements of project management are time, resource and quality. I think if you manage them well, you should have no problem working only in the work hours. If my assumption is invalid, then you need to work on how much you want to get paid. :-)
Hope they are helpful. All the best to your work and life. :-)