That jacket pattern I drafted tore apart at the shoulder seam after 6 wears
I spent 4 days hand-stitching a wool blazer from a pattern I graded myself, and on the third time wearing it to a coffee shop in Richmond, the whole arm popped loose - so do you think the issue was my seam allowance being too small or the fabric weight being wrong for that style?
Bet it's the seam allowance. I've had the same thing happen with a heavy wool, even 5/8" wasn't enough on a shoulder curve. Next time try 3/4" and clip your curves deeper before you turn it.
Ugh yes, this is exactly what happened to me with a boiled wool jacket last fall... even 5/8" puckered like crazy on the collar curve. Clipping deeper made a huge difference, almost as much as bumping the seam allowance up.