I know I am speaking to a mostly sophisticated group of Skymiles earners, but also note this T&C:
Threshold Bonus Miles:
Bonus miles under this offer will only be awarded in the stated increments for the activity levels described. For example, 8 unique partner activities would result in only 6,000 bonus miles. Please allow 10 to 12 weeks after the promotion ends for all bonus miles to post.
in conjunction with this:
Unique Partner Activity Bonus Miles Awarded
3 3,000
6 6,000
12 12,000
20 20,000
25 25,000
So, if you get to 11 activities, you had better do another, or lose out on lots of points!