Yes, that does leave a lot of latitude, but I wouldn't call it latitude for error, because it simply isn't that particular.
I didn't do anything elaborate on mine, like measure the pounds of pull. I simply tightened them up so that they were snug but certainly not strained. After a couple of weeks, they stretched a bit and I tightened them up some more. Since then, they have been fine.
There really isn't a tight tolerance on this: You can kind of intuitively see when they are too loose and would be likely to slip. And you can also intuitively feel when they are too tight, because they feel like they are under strain.
This may not sound very helpful, but as long as they are a snug but not strained, you shouldn't have any problem. They actually have to become pretty loose to start missing steps, and it is usually pretty obvious that they are too loose when this happens. (They almost have to be drooping before this happens.) And you also don't have to really crank them down tight to ensure that they will work properly.