I’m not aware of any company that develops employee scheduling.
Most carwash operators and companies develop their own staffing models.
In order to maximize wash revenues, staffing should be based on volume trends over the past 60 days and specifics like weather, holidays, season, etc.
Cars per hour and volume report are needed to analyze past trends for scheduling.
Staffing model begins by identifying what positions need to be filled to maintain productivity.
Next, establish cycle times for services and staffing needed to meet these times.
Establish management schedule first. Say, manager and assistants work 54 hours per week, five days per week. Service manager works 40 hours, five days per week.
Manager is off Sun and Mon, assistants and service manager are off Tues, Wed or Thur. This ensures key staff is scheduled for busiest days of Fri and Sat.
Employee schedule depends on facility configuration.
For example, are you pre-vacuum/post wash, on-line/post wash, all post wash or pre-vacuum/on-line/post wash?
Each has different scheduling requirements based on expected cars per hour.
Make a master schedule then fine tune it.