I may not be an instructor but I have raced one thing or another since the mid 60's and I haven't double clutched since I last drove an old fire truck with bad syncros. If you shift gears and it doesn't grind, the syncros are working and you don't need to double clutch. I still can't figure out what the purpose is, other than making your shift times slower.
And Dangerous, if you double clutch while drag racing.....well, I'm not even going there.
You ain't old enough to have that much to bitch about!!!