There are only 4 options, because this was my first stab at controlling how to add events.
I did not have much data to go on, so I went with recommended up to 2 as default, and added "always" and "never" for good measure. Up to 3 is more of the option for more adventurous Adventures players. Both random options rely on probabilities calculated with number of cards and events selected. So including 3 events would only happen only about 5-6% of time (for all 236 cards and 20 events). I can change/add to those options, based on the feedback I receive.
edit/addition: I just realized, why I included option to include randomly up to 3, and not 4 or more events. Calculating probabilities, I was getting little over 1% for 4 events, and then less than .5% for 5 Events, and less and less for more Events. So, I didn't want to include it, as it could result users claiming it never happens or app is buggy. Say you set it to up to 10 Events, then you would have a chance of 10 Events happening about one per 10 million (if my calculations were right). Sure, I could implement it other way and just allow each number of Events happen 1/21 (0 Events + 1-20 Events) of the time, but then someone else would claim that it is invalid as well.