To add a little humour into the subject of forgetting to check the flaps position after selection. In the late 1950's I was a flying instructor at RAAF Base Townsville on Lancaster Mk 4's - otherwise known as the Lincoln. I was converting my Commanding Officer to the type. His name was Wing Commander Cy Greenwood. Cy wore a bristling moustache and was a no-nonsense personality who did not suffer fools gladly.
During WW2 he was a Beaufighter pilot based at Coomalie Creek airstrip south of Darwin. During a raid on a Japanese seaplane base in Timor he was attacked by four Japanese Zero fighter floatplanes. His aircraft was shot down and Cy ditched a mile off the coast. His navigator was killed when the Japs strafed the ditched Beaufighter. Cy was repeatedly fired upon while in his life jacket but fooled the enemy pilots by ducking under water as they came at him.
He swam a mile to shore but was betrayed by local natives and caught by Japanese soldiers. He was beaten up and eventually incarcerated in the notorious Changi prison. He was repatriated after the war and remained in the RAAF becoming the CO in 1948 of the RAAF contingent flying supplies in Dakotas to the starving German population during the Berlin Airlift of Cold War fame.
See:
https://en.wikipedia.org/wiki/Berlin_Blockade
In 1959 he was posted to Townsville as Commanding Officer of No. 10 (Maritime Reconnaissance Squadron) where I did his Lincoln conversion..
One day we were doing circuits and touch and go's. On final he requested full flap which I selected for him. The flap lever in the Lincoln was a vertical lever in the fuselage floor. There were several positions available. Up, Neutral and Full Down with intermediate selections in between. In each case the flap lever was set to neutral once the required setting was attained. The threshold speed for full flap was 105 knots.
At 500 feet on final he requested full flap and when the flap indicator indicted it was fully down I returned the lever to neutral. Around 100 feet the Lincoln fell out of the sky and we landed with a huge bounce. I had no idea what had gone wrong. The Wingco gave a frightful oath and firewalled all four engines for a go-around. He called for the flaps to be retracted to half as part of the go-around procedure. When I reached for the flap lever I saw that the flaps were already fully up.
Looking down at the flap lever I realised with dismay that the selector was just out of neutral and it was obvious that during selection to neutral after full flap had been attained, I had inadvertently gone past the neutral position to up. Hence the loss of lift and heavy touch-down. I apologised to the CO and assured him it was my fault for his heavy landing.
He looked down at me with his moustache bristling but merely grunted. The rest of the circuits were uneventful.