The one point we are all missing here is practice FLs and real ones. In practice we can chop the throttle at 2000 feet 1500 feet 1000 feet reality is that the cruise is the least likely time you will loose an engine.
More likely in the climb out at 200 feet 400 feet 600 feet where your time is very limited for looking at causes. As BPF states most are pilot mismanagement or not complete loss of the engine.
"tell your instructor the field at 2000ft, then make sure that's the field you set up for".
I WISH Engine failures were all at 2000 feet
plenty of time !run through engine checks, set up the glide ,fly a pattern onto the chosen one and bingo but sadly reality is not like that.
Hence why its vital to be decisive and flexible in your thinking and actions and be ready to change if the situation changes.
You may restart if you have altitude, you may keep the engine running and decide to make it back then find it stops and you are faced with a new set of circumstances.
You may select a field and get it wrong do you have a plan B or C in mind and are ready to change that.
There are so many variables and a certain amount of luck too in a real engine failure and a successful outcome.
One pilot picked a field landed short wrecked the aircraft and sustained minor injuries on his left was an even better field which after the crash he said he discounted because it wasn't into wind. He could have turned into it but didn't (( Hindsight is a great thing BUT?
Most of all keep it flying or for almost certain you will end up dying if you don't
pace