OK. I had not remembered Luke throwing and missing once, but when I read this thread it jogged a memory NOT of Luke throwing and missing, but of when I finally saw Starwars on pay cable (maybe 3 years (ca. 1980?) after seeing it in the theater.) I now vaguely remember feeling that scene was not shorter on TV.
I don’t remember if he threw and missed though that does seem vaguely familiar now that you mention it, but I do remember the scene seeming to be a over quicker.
It may just be that at 4 years old and seeing it for the first time in 1977 that I really was terrified that they were about to die and that made it seem longer, but it is interesting to me in light of all the people who seem to remember Luke throwing twice.