I did 'no power' flight in my last sim. (RJ100)
Made a mess of the first one but did a nice landing off the second.
Personally I thought it quite useful. I really had little idea of how far it would go from a given height and was quite surprised at how well it did.
I hope to never use the info for real, but it was only 10 mins in the sim and it probably trebled my chances of a good outcome should I ever run the sucker out of gas!
.
(heaven forbid
)