Uncertainty in predicting the future Incomplete project scopes Estimating a project's time and cost should be __. Multiple choice question. always done using a bottom up approach. only done using a top down approach. a continual process rather than a one time event. something only done by experienced project managers. Time and cost devoted to managing rises exponentially as the number of people and different disciplines involved increases on a project. Many firms collect time and cost data through the project office . As projects progress, a manager obtains a better understanding of the project. This may lead to major changes in project and . Mega projects often cost much less than expected, but they overdeliver on benefits they are to provide. Direct project costs can be tied to project deliverables or work packages