Finally, there are a couple of things that are not quite right with my analysis of the sticky targets. I haven't posted these before, because in the end, my formula is just a recommendatation, and one that I am pretty happy with.
First, the threshold Var/EV, and requirement that BR=n*Var/EV, where 2<~n<~4, is derived using risk-of-ruin arguments. Here I am using the same pricing system for marginal variance, that is not really related to your risk of ruin. If you wanted, you could derive a higher target by dealing with the sticky-bonus deal as a single bet, and requiring that it doesn't exceed your threshold Var/EV. That is not what I am doing. I am comparing two wagers, one a sticky bonus with target X, and the other a sticky bonus with target X+dX, and look at which one is more attractive.
I believe I've shown before that pricing marginal variance is different from pricing overall variance in this recent post:
Advanced Risk Management
If I used the ideas in that post, I would make a higher target recommendation.
Second, the BR=n*Var/EV is derived using a normal approximation. In calculating the target I am looking at a +EV bet where you risk a lot (Target-bonus) to gain a little (dTarget). We know that for the same EV and Var these bets are less attractive than coin flips for which normal approximation would hold. A converse situation (risking a little to win a big jackpot) is discussed here:
Risk of ruin when central limit theorem hasn't kicked in
If I used this concept, I would make a lower target recommendation.
Oh well, I guess the two corrections cancel somewhat, and so I keep my recommendation.