Requiring and using a modulescript inside of a modulescript?

You can definitely use ModuleScripts inside of ModuleScripts. I'm not sure what you're trying to achieve with your code, but it looks like you're confused about how ModuleScripts work.

ModuleScripts can return two things: a function, or a table.

ModuleScript (in ReplicatedStorage)

local double = function(x)
	return x * 2
end

return double

Usage:

local double = require(game.ReplicatedStorage.ModuleScript)
print(double(2)) --> 4

Or it can return a table (in Lua, a table is basically a list).

TimeModule

local Time = {}

function Time.seconds(seconds)
	return math.ceil( seconds  )
end

function Time.minutes(minutes)
	return math.ceil( minutes * secondsPerMinute )
end

function Time.hours(hours)
	return math.ceil( hours * secondsPerHour)
end

function Time.days(days)
	return math.ceil( days * secondsPerDay  )
end

...

return Time

Usage:

local Time = require(game.ReplicatedStorage.TimeModule)
local week = Time.days(7)