Many many hours are wasted trying to figure out, and figure out ways around the complicated appropriations issues. Colors of money, expiration dates, Severable or Non-Severable tasking. Either the number of exceptions and ways around the rules need to be reduced or the reasons for having so many types of funds, allocations and other complications needs to be revisited and simplified.
At year end in particular, managers waste thousands of hours searching for Contract vehicles anywhere in the DoD (and other agencies) to get money to particular contractors to complete work. Sometimes the money is left because it was budgeted for a breakdown that didn't occur, sometimes it was just a project that completed for less than was budgeted. However the funds become available, it leaves lots of money to be obligated at the risk of losing it from your budget for the following year. That mentality wastes huge amounts of taxpayer funds each year. Unfortunately, like the proverbial hydra, every attempt to minimize the year-end spending spree just creates more creativity and ingenuity to get around the rule. The work necessary to get around the rule is worthwhile to prevent having your budgets cut in subsequent years.
The closer Congress tries to monitor the money flow, the more complicated the games become to get around the rules and to accomplish the mission despite their oversight. Congress needs to develop a level of Trust but Verify. Trust people to do the right thing, verify that they have done the right thing and otherwise leave them alone. A few bad apples might appear, but rather than punish everyone with complex and complicated rules, Congress needs to deal with the bad apples and let the rest continue on their own way.