There’s no such thing as a perfect budget. You can plan meticulously and down to the penny, but at some point, something unexpected is going to happen. Equipment can break, weather can cause massive delays, a rash of employee sickness may result in lost work hours–anything can happen. You can expect that something will go wrong, but it’s impossible to know exactly what. Even the most demanding foreman or the most scrupulous designer of an MDU has things that are out of their control.
Because of this, it’s important to anticipate everything that is in your control. This means being incredibly meticulous and reducing the aspects of the job that previously might be considered unforeseeable. Because while you can’t predict a week of rain, you can use the budgeting phase to make sure that everything that is in your control is, well, controlled for. This includes a bunch of factors many people don’t think about.