Novice stringer here. When I use string off a reel, I cut longer pieces to make sure I have plenty. However, I have to do a 18x20 Wilson BLX Pro Tour racket with gut and I don't want to screw up(again). The gut comes with 20' length. The specs say 20' for the mains. I am using the Stringway ML120 and I have come up short before. Is 20' long enough?