My last place used to do position budgeting based on previous year's pay hours. Which may sound good on paper for stable departments but...

2016: 4 people in the position who worked fulltime throughout the year. Their budget for 2017 is 4.0

2017: 1 employee left in July. But due to bureaucracy it took 6 months to even try to get the position posted. Calculated pay hours for the year were 3.5 so that's the employee budget for 2018.

2018: 3 employees still in the position doing the workload of 4. In February the position finally gets to the employment board but since their budget is 3.5 they're only approved to post a part-time position. Takes 4 months to get it posted, applicants and interviews. By August the position is finally filled with a part-time worker. One of the original 3 is finally sick of the BS and leaves in October. Calculated pay hours is 2.95 for the year and so budgeted 3.0 for 2019.

2019: Current budget is 3.0, they try to get approval to backfill the employee who left in October but current staffing is 2.5, they won't allow 2 PT employees so they're able to negotiate converting the PT to FT, which becomes effective in April. Calculating payroll throughout the year with the status change, the budget going into 2020 is 2.8 which means they'll never get back to 4 employees.

This is a VERY realistic scenario which lead to once easy going departments becoming staffed with burned out, bitter employees.