I do basically the same thing, but with a bare shaft.
1. Shoot bare shaft with weight I want. If it goes into the target with nock pointing left then I need to shorten(stiffen) the shaft.
2. Cut shaft, reattach point
3. Shoot
4. Repeat until my bare shaft enters the target at least close to straight at 20 yards, or until it just starts to impact going the other way.
5. Cut the rest of my arrows to the same length and fletch them.
Since I usually don't tune each arrow individually, I might get one or two that don't fly as well as the others, but I can live with it for the time it saves.
When I finally get around to making some hunting arrows, I'll probably tune each one individually.