How quick is it to get 100 shards for Farmboy Luke?

Have to do three refreshes, use the bonus energy and the 120 you get naturally you to do 65 sims a day, provided you don't get terrible RNG and get the 1:3 droprate you'll get around 22 shards a day from cantina.

Not guaranteed though and you are set to run out of crystals after 3 days may be 4 depending on how much you get coming in. I would consider the Luke pack as it's guaranteed shards.

a 1/3 drop rate on an 8 energy cantina node and you need 100 shards.
3 * 8 * 100 = 2400 energy needed to be spent on cantina to get those 100 shards. You have 8 days so that's 300 energy a day. You get 120 every day from time passing +45 at noon, so that leaves 135 energy beyond what you get for free. Buy a refresh a day, plus one extra some other day and you should make it on the last day.