Events Budgeting

Clear process descriptions or pure estimates? The practice shows that both statements have their justification. A clear definition of the budgeting process makes sense, but much more important is the clear distribution of tasks within the event team and a detailed description of the various types of costs and revenues. The application of certain project management tools are helpful, so the event budget is also the first guideline for operational implementation. In which amount the respective costs are then budgeted, is really often estimated and due to the experience of the event managers, so also my experience. What do you think?