What I have felt is that the more open I can keep my elbow/arm extended while also away from the body the slower I can come through but still generate the same lag/release speed and this has really made it so much more effortless to get the same distance. I think what happens to many people is that the elbow moves more travels more like a standing V rather than layed down V.
Everybody I have shown this to has also said it felt weird at first and I suppose that was why I had such a big aha moment when I figured it out, quite litterally I doubled my forehand in one throw and at the same time it was maybe 20% of the perceived effort.
Yes south east to north west is a good description but since you also rotate the upper body compared to the target direction the movement isnt so much but both parts are key to be able to move the arm so that the elbow can lead.
Went out for a quick fieldwork, i have to say.. focusing straighter arm, leading more with elbow ouside in diagonal was great tips. Felt easier to lead with the elbow. Still one or another disc turned over and Still some pain but overall an sucsess. Aiming was slightly harder tho, some throws released to the right. The layed v shape elbow tho kinda hurt, i just did it like that a tiny bit.