Somebody asked me this question in the comments section of the wiki and I thought that some of you might have missed my answer there yet find it interesting.
As you know, during the Zomboss battle of Penny's Pursuit, once you deplete the required number of health bars, the battle enters a "bonus" phase, with various kinds of loot dropping - silver coins, gold coins, gems, and sprouts. The loot drops only from killed zombies - not from the boss.
The question is - what is the exact loot dropping algorithm? Do you need to kill N zombies or what?
The answer is this: The loot drops from a killed zombie every N seconds, where N is a random number picked from a range (minimum-maximum). N is not constant, meaning that after the drop another N is picked for the next drop.
The ranges are different for the different kinds of loot and also depend on the difficulty of the level. Here they are:
1-Chili
Loot Range (sec)
| Gem | 18-22 |
| Gold | 8-13 |
| Silver | 3-5 |
| Sprout | 50-60 |
2-Chili
Loot Range (sec)
| Gem | 15-22 |
| Gold | 6-13 |
| Silver | 2-5 |
| Sprout | 45-60 |
3-Chili
Loot Range (sec)
| Gem | 12-22 |
| Gold | 4-13 |
| Silver | 1-5 |
| Sprout | 40-60 |
So, for instance, if you're playing on hardest difficulty, a gem drops every 12-22 seconds. Knowing how much time for the bonus phase your strategy leaves on the timer, this should let you estimate the minimum and maximum amount of gems that you can get.