Is ViewState required for CompareValidator or other validator controls

[Guess]

I have seen examples that seem to indicate that if we extend a
validator, the extended properties must be preserved in ViewState.
That seems unnessary to me since we usually will declare the validators
on every trip to the server.
Am I missing something?.
The example I am thinking about, the validator class declares a property
ControlToCompare, this Property preservers and loads its values from
Viewstate as follows:
public string ControlToCompare
{
get
{
string temp = (string)ViewState
["ControlToCompare"];

if (temp != null)
{
return temp;
}
else
{
return string.Empty;
}
}
set
{
ViewState["ControlToCompare"] = value;
}
}
[This followup was posted to microsoft.public.dotnet.general and a copy
was sent to the cited author.]