There are lots of stories about the cabeceo; the ones that worked, the ones that didn't, the ones that worked but only just, the ones that got away. Here's one of mine.
My friend arrived much later than me, and we were seated at opposite ends of the room. I was looking forward to a dance with her, but she'd been given a seat behind a large gentleman, and most of the time I couldn't even get a glimpse of her. She danced one tanda, then disappeared again. & then there was a cortina and suddenly I could see her smiling at me and nodding. I stood up and walked firmly across the floor.
However, just as I arrived in front of her I became aware that the guy sitting next to me was walking beside me, in the same direction, and I saw a look of consternation on her face. Had it all gone very wrong? My confident walk faltered: I envisaged having to walk straight past her and on to the toilets, as if that had been my confident intention all along. & then, equally suddenly, it was resolved. The girl sitting next to her rose to greet the guy walking next to me. I greeted my friend, and two happy couples took to the floor.
It usually works pretty well, once you get used to it. Perhaps it would be less nerve-racking if we used texts... but you wouldn't want to spend half a tanda fumbling with a mobile!