Found this from last year, you do have a point, they tend to be at $1600 more so statistically than elsewhere. However based on this find below they are located at the top as well but very very rare. Haven't found a diagram for round 1 yet.
http://digg.com/2018/joepardy-daily-...ability-mapped
I am not sure statistically though if James is actually finding that many more DD's than the average championship run we see. Over the first 22 games he found 7 or 8 more than Ken, which is higher but... we have to factor in his rate of correct answers is higher than Ken which means he picks again more so thus more DD finds. It is NOT enough to find a DD on its own, the amount you wager is a huge factor obviously as well.
Looking at past DD wager/win ratios is fun too.
Bottom line, guy is a machine with the buzzer has a great strategy and without the knowledge wouldn't be able to pick and find the DD's before the other contestants, end of story.