Wouldn't a second one take you less time than the first, since you've done all the analysis and worked out the best way to do it?
1. each one is different, though similar. the measurements are custom to the wielder, and the curve is somewhat influenced by the grain.
2. this current bokken is the fifth bokken I have made in the last ten years
3. though it has been a while, I'm no stranger to working metal by hand
so, nope: any subsequent bokken will take about 100 hours to fabricate.