One thing that I've noticed is that Y% is often a constantly moving target whereas X% is a bit more static. The arbitrage opportunities can and do dry up. Typi

One thing that I've noticed is that Y% is often a constantly moving target whereas X% is a bit more static. The arbitrage opportunities can and do dry up. Typically the larger the arb, the faster it dries up, at which point you're back to earning X% but with more overheads. At most you can probably be sitting on Y% for a few months before you need to find a new strategy.