I'm a leftie, so the blocking (and the mini ground plan) go on the left hand side, with the script on the right. So I COULD use the blocking script to call cues... but by the time we're done with tech week, there would be no way to legibly mark cues.
I know it's a waste of paper, but I'm very deliberate about recycling and reusing, so I allow myself the indulgence of a separate calling script. Often scripts are sent electronically, so I can adjust margins and enter extra space at cue-laden points, giving myself the best chance to read the darned thing. (And, of course, if I get hit by a bus on the way to the show, whoever ends up calling the show won't have to guess what I meant by "ROS XDS L5.")
Once we've gotten through previews, I spend the hours before opening night with a box of rainbow Sharpies, transferring cues to the calling script. All stand-bys are orange, LQs are green, etc. Action (go, standby) is denoted by pencil... it could still change... by a line from the "insertion" point to the cue name on the right margin. At the top of each page, I write the cue that we should be in at that point; at the bottom, I write the act/scene. And by the time I'm done, I've looked at all of my blocking script notes one last time, and incorporated any changes from the last preview. It's anal retentive, but that's why we do what we do...