Its been 100% for me. If it looks like a cone shell or a butt plug, its a girl. Generally it will have a single hair growing out of the tip of the cone shell shaped pre-flower. If there is no hair, wait 2 days and check again and the hair will usually be there.
If it looks like a ball being held by a bird talon, its a boy. Won't matter how long you wait, it doesn't really change its appearance until its ready to start making pollen sacs.
The last picture of Stankberry #4 is a tough one. I looked more boy like initially but when we checked the next day, I wasn't so sure....seems like its making me wait for it. If its a girl, it will throw a hair out of there in the next day or two.....otherwise it is likely the boy we thought it was initially. Hoping its a boy really, its the slowest grower out of the 4 Stankberry and 4 DTF plants, so I can cull it for some space. I am keeping Stankberry #1 to see if he is going to be a suitable male to try some F2s with.