Rubick is an employee of Radiant Financial Corporation Ltd$.$ He has been assigned the task of preparing a budget for the company. He observed that in the previous year budget was prepared on the basis of the previous year's figures and in various cases either the budgeted amount was lying unutilized or it fell short. He wants to avoid such a situation in future Budgetary Processes.

Explain the reason of over budgeting$/$shortfall in the above$-$listed case. Which of the budgetary techniques should be used by Rubick so as to avoid Over$-$budgeting$/$Short Budgeting?