Which is better, pre-making a part or defining a part in a script?

For example, say I want to clone a specific part several times in a script. What would be more efficient, to define it all as a variable at the beginning of the script or to actually create the part and place it inside the script?

Defined Part Example:

local Part = Instance.new("Part")
Part.CanCollide = false
Part.Size = Vector3.new(2,2,2)
Part.Transparency = 1

script.Parent.Touched:connect(function()
local newpart = Part:clone()
newpart.Parent = workspace
end)

Pre-Made Part Example:

local Part = script:FindFirstChild("Part")

script.Parent.Touched:connect(function()
local newpart = Part:clone()
newpart.Parent = workspace
end)

I find it confusing because with the defined version, the part doesn't have to physically exist inside the script yet, whereas it does with the pre-made example. Which one would be better to use?