[SDPhantom]

In general, I have a variable keep track if I have hooked the script and only do so if I haven't.

For example:

local function OnScript(self)
--  Do Stuff
end
 
local Hooked={};
hooksecurefunc(SomeFrameMixin,"SomeMethod",function(self)
    if not Hooked[self] then
        self:HookScript("ScriptType",OnScript);
        Hooked[self]=true;
    end
end);

PS: I don't see a reason to not use :HookScript() when you're essentially reinventing it anyway.