Sometimes it's not even in your own cockpit!
I was teaching in a CT recently out of an airfield where finals is over a large town. I know the place well.
My philosophy is straightforward - there's only one engine, it has potential to stop, however small a chance, so we come in high, and only start descending when quite sure we can make the runway, or at-least something large flat and green.
I had three PA28s in an hour of circuits do a panicked go-around because the local commercial students couldn't cope with the idea that this aeroplane that had been doing the same speed as them downwind was now doing a 50kn steep glide approach every time. Eventually the tower told me to ignore the noise avoids and fly a much tighter circuit than they publish because of the trouble I was causing by insisting on flying so that if the engine stopped I'd make the runway
G