This is a topic dedicated to the study of element shard production! Several things I've read and found are as follows:
1. Laughter is the most common shard
2. Honesty seems to also be quite common
3. Magic seems to be the rarest (that or loyalty)
4. The longer the production time a building has, the more likely it is to produce other elements
Theories: 1. blueruby: The more higher rank ponies that work at a certain shop, the more likely it is to produce elements other than laughter
2. Depending on the mane 6 pony being focused on, the more common that pony's respective element becomes.
3. Activating an element stone boosts that elements likelihood of being produced.
So these are observations and theories that I have seen, read and made.
Post yours below so we can confirm and develop new theories and understand this better, because lets be honest... parasprites are parasprites... --- Bears, Beats, Battlestar Galactica...... --Dwight Schrute(Jim Halpert) "THE OFFICE" FOREVER