Yep they fine..
Long lines are very handy indeed, not only for training but at times when you want to give your dog some freedom but do want ultimate control! Such as when walking in new areas or where live stock might be around etc..
But do be perpared to be tangled up around people if they are playing with other dogs, and/or trees as they will go the opposite way than you

And it's wise to wear gloves cause believe me friction burns do half hurt...
And I've found knotting the line in several places is rather helpful for the time when you allowing them to tow the line around, if they ignore the recall and dash of, you jump on the line and wait for the knot to hit the feet!
I actually make my own up (I'm a cheap skate

) when they pups and you'll just starting the recall training, I tend to use a shorter line length as you'll starting a lot nearer to them, and you get so tangled up with a real long one..
At the moment my long line is being employed tied to a ball or dumb-bell in a attempt to encourage Ellie to bring back balls etc on commande, as at the moment she nicks other dogs balls and see's it has a game to try to entice you into chasing her to get it back! Which of cause we don't do just wait until she gets fed up to retrived it