No unless someone who knows UTC wants to show up on North American thursday (a day I cannot play on, this is likely for other people too) and on friday that's too early, I wouldn't even be home from school.
Unless it would make more sense to say...
Friday (PST, MST, CST): 01 to 07 UTC
That makes no sense. Since the new day is a Saturday in the time that can be used for everyone in the world and off the world, it will say Saturday.
Now, I cannot be back until around 01 UTC on "Friday" (Sat UTC) unless you'd like me to start the game when I am not likely to be at home. Trust me, I made these times so that I could be here, based around all the non-flexible things that I have to do. And so that I don't keep everyone up way late (especially Yqt and other people over east). If it works for you, you can play (hurray!), if it doesn't work for you, that's unfortunate, you won't be playing.
Also, I have to say, this makes no sense, at all:
saturday: 21 to 05 UTC