It's fine and probably preferrable for the GFCI outlet to be the only one protected. It's going to the garage and the rest of the outlets are on a back wall in my den. The reason I would want to use a junction box is because the 1st outlet on the circuit is the only one I can get to without demo, but it's a long way from where I am putting the garage outlet. So if I chain the remaining 4 outlets from the GFCI, I'll have to make a long run to the GFCI and then another long run back to that 1st (now it would be the 2nd) outlet. Using a junction box would be easier because I would only have to run a line one-way to the GFCI, and more importantly I won't have to buy another roll of wire because I have just enough to do it that way.
So I guess my real question is: CAN I run a single-outlet GFCI branch + a standard outlet branch with 4 outlets, from a junction box at the beginning of the circuit? That would be the easiest thing to do in this situation and would allow only the garage outlet to be GFCI protected which is technically what I need anyway.