The two that come most immediately to mind are the two that Kevin mentioned previously, Australia and New Zealand. In that situation, when you look back through their records on why they actually set up that system, they found, to the point that you raised, that it facilitates members in their short timeframes to actually focus on the incremental issues and the material issues that are flagged in the government's policy document and the budget. It allows them to focus on those aspects within the appropriation bill. So instead of looking at the 95% of things that are routine, you're looking at the 5% of things that are novel and new and potentially the government hasn't tried before, and you can kick the tires and determine whether it makes sense or not.
The other benefit is that in both of those jurisdictions you can look at the individual departments, and there is a certain beauty in being able to look at the individual departments and roll everything up to the budget. When you look at the individual plans by department and you sum everything, it adds up to the budget and you're able to reconcile the numbers perfectly.
As an accountant, I like numbers to balance, but for parliamentarians who might not necessarily have a background in financial issues, there is a certain facility in doing that and knowing that if there is $5 billion for a certain department, say Public Safety, that same $5 billion will be showing up within the budget document itself.