Because the drop rate is so low (about 30%), it's not as uncommon to go long stretches without a drop as you might think. You get 165 energy per day (45 + 5/hr x 24), for about 10 attempts without a refresh (165/16). The probability of going 0/10 is (1-.3)^10, or about 1 in 35.
Now you've got 265 shards to farm for each, for a total of 530. At a 30% drop rate, that's 1766 cantina battles you'll need to do (530÷.3). So with such large number of attempts, you'll be going 0/10 pretty often. It seems like you might just be happening to get those streaks on Han rather than Chewie.
I've farmed Capt Han, Deathtrooper, Sith Trooper and the vets from the 16e nodes, and they all seem to take the same amount of time, plus or minus a couple of days. Kinda like the stock market, you have to look at the long term rather than daily changes.