Many people who engage in stablecoin yield farming on the chain are easily caught by an unseen cost—the asymmetry of flash swap fees.

Take a leading stablecoin protocol as an example. Swapping USDT for lisUSD with zero fees sounds very attractive. But want to swap back? Then you'll have to pay a 2% fee. There are also constraints on flash swap limits, which directly determine your liquidity inflow and outflow.

Looking at it from a different perspective makes it clear. Suppose the annualized yield of the stable pool is around 7.92%. That 2% cost would require nearly three months of interest to recover. If you don't plan to lock in for that long, this flash swap isn't cost-effective at all. Savings products have even lower yields, around 3.96% annually, with a payback period close to half a year, making the risk-to-reward ratio even worse.

So the core strategy is actually simple: only perform flash swaps when you're sure the funds will stay on the chain for a sufficiently long period. Before entering, precisely calculate the combined costs of time and fees, rather than just looking at the nominal yield.

Finally, pay attention to the flow of incentive funds—the protocol's voting emissions will directly affect the actual returns of a certain path, which can also change your payback period.