Of course, the fewer attempts you need the better, but whether you clip the anchors on your fifth try or your 50th, you have redpointed the route. Most people can redpoint nearly a full number grade higher then they can on-sight. So, if you can consistently climb 5.11c first try, then a 5.12b should be feasible after a few days practicing and attempting the route. One 5.12b on-sight does not mean that a 5.13 redpoint is just around the corner. The following will teach you the key danger zones of a one-pitch sport climb and how to handle them.
Sport climbers take frequent and forceful falls.
Most serious sport-climbing accidents stem from mistakes made before the action even begins. Prevent them by running through the following checklist before you step off the ground. Also check the knotted rope is correctly threaded through the waist belt and leg loops of the leader's harness. Double check the belayer's screwgate carabiner is locked. If there is any doubt, tie a knot in the tail end of the rope or have the belayer tie it directly into his harness.