Though this would be faster for a lot of data:
Sub sample()

    Dim Sweep As Long
    Dim Engineers As Collection
    Dim Engineer As cEngineer
    
    Dim vNames, vDates
    Dim lr As Long
    
    Set Engineers = New Collection
    
    
    For Sweep = 6 To 14
        Set Engineer = New cFranchise
        Engineer.Name = Cells(Sweep, 5).value
        Engineers.Add Engineer, Engineer.Name
    Next Sweep
    
    With Sheets("JobData")
        lr = .Range("A1048000").End(xlUp).Row
        vNames = Range("BB2:BB" & lr).value
        vDates = Range("X2:X" & lr).value
    End With
    
    
    For Sweep = 2 To lr
        Engineers(vNames(Sweep,1)).AddDate vDates(Sweep,1)
    Next Sweep

End Sub
But I reckon a pivot table would be even quicker