: However, any time I update a manager, it takes several minutes
: for the array to recalculate the 3000+ lines. Can you think of a
: faster method?

How about tracking the unique  manager names in a dictionary
object? Use this as a user defined function. I named the test
range "managers". This is a generic function. It should work on
any range of values.

=UniqueCount(managers)

Function UniqueCount(rngCells As Range) As Integer

Dim vCell As Variant

' Setup dictionary
Dim Unique As Object
Set Unique = CreateObject("Scripting.Dictionary")

' Populate dictionary
For Each vCell In rngCells
If Not Unique.exists(vCell.Value) Then Unique.Add vCell.Value,
vCell.Value
Next vCell

' Count unique items
UniqueCount = Unique.Count

' Clean up
Set Unique = Nothing

End Function