T3 doesn't have any particularly overly quiet periods now, save the end of the day before the last Ryanair heads out.
Yes, there are a lot of based aircraft, but Flybe actually use more away based flights than based, and Ryanair also have a lot of away based flights. Then there are airlines like AA, Air France and Vueling away based, as well as the high frequency BA/KL flights.
So, not as wavy as one would expect.