Sorry Fella you are mistaken and KK is wrong to say that betsize does not affect EV. What Andy says above is correct.
I have no idea why KK continues to say this when it was proven to him on the CM thread that Etherz posted the other day:
Bryan the Casinomeister asked KK to remove his affiliate tags because it was deemed the lowrolling 'strategy' of gradually increasing bets he was advocating had no mathamatical validity. In other words it would not make you a winner but simply a recreational player. Which is fair enough it that's what you want to do but I assume most people here are interested in making money over recreational play.
The reason why it is better to bet big and go for say a 3x d+b target is because the bonus is PRE WAGER. The theory is the same on whatever pre wager bonus you do, it doesn't have to be slots. It is exactly the same as the sticky bonus idea.
By repeatedly busting you avoid most of the WR and only pay the WR tax when you make a big win. The higher the target the more EV you make. Ofcourse eventually you will end up mkaing a huge amount of EV but go completely broke . So in the real world you might want so set a moderate target of say a double up.
But what ever target you set the important thing is to bet big at the start so you either hit it or bust as early as possible. This is where it gets tricky with slots because getting the correct betsize is hard due to the different variances of different slots. Actually this is where KK's slots knowledge is useful because he has good data on the variance of Rival machines and also the average spin time you need to hit a feature. So on one slot even a £2 spin may be enough but on another one you may have to go £7.50 to get the same level of variance. Obviously once you hit your target you move to a low variance machine and bet small and grind.
This is where I will ALWAYS disagree with KK. He says 'start off small, if you don't hit a feature gradually up your bets.' But hopefully everyone here understands the features are random and your previous spins have no bearing on your next ones. If you are not clear on this you need to revisit the Martingale (aka Red Mist ) strategy and understand why that can never work.
I say bet big at the beginning, hit target, then grind. But use KK's data to get you betsize right so you are not over or under variancing yourself.
Please remember this will only work for a PRE WAGER bonus. Don't try this at Lads .