The last time I took off from Aero Expo ( or was it the Jubilee airshow ) at Sywell, it was akin to scrambling fighters in the Battle of Britain. The field was closed until the airshow finished and on re-opening everyone wanted to leave at once... and everyone did. Aircraft of different types, and hence speeds were departing concurrently on both the grass and hard runways with very tight spacing. It made for an exciting climb out and I was glad when I left the circuit, and the excitement, behind!
I didn't find arrival that bad, but again you are relying on other pilots to be familiar with the published arrival procedure.