This will not only save time but also give you a lot more options to enhance your forecasting by enabling you to work on different levels of detail at the same time. With an 80/20 approach you will be able to focus on the most important budget drivers and let the rest be calculated automatically, but still be broken down to the lowest desirable level for follow up on actual vs. budget on all levels.
Being able to do detailed budgeting on customer/article level for the most important customer groups/customers, new customers and new article groups/articles, you can enable close follow up on both strategic and tactical goals.
If you are able to document assumptions and add action plans to your most important business drivers, you can establish a performance management system that most certainly will make significant impact on your bottom line.
If you want to know more about InfoSuite Budget, which is integrated with InfoSuite BI, you can learn more here.