Twilkes
Guru
Fwiw, I have a Cannondale that has had a BB servicing and was nearly brand new when I got it and it has always had less than a turn of the cranks if I try to spin it backwards. I noticed it when I first got it, but it's had no bearing (pun intended) on how fast it rides or how fast it freewheels so I think it's just some bikes behave like that.
Not that this will make a heck of a lot of difference to ya, but replacing the chain let me clean all the bits of the drivetrain that don't normally get cleaned very well, and the culprit that was stopping the cranks from spinning backwards very much was the upper jockey wheel. If I spun it there was hardly any free-spin before it stopped, but equally I could move it with a tiny amount of finger pressure so I doubt it had any effect when pedalling forward.