Slippage — the gap between the price you wanted and the price you got — is a cost on every trade. On 1DTE and 0DTE SPY options, it's amplified to the point of being decisive. A short-dated contract can move a large percentage on a small move in SPY, and the fill you get in the first second decides whether the trade is worth taking at all.
Why short-dated is worse
Three forces stack. The bid-ask spread on short-dated options is wider relative to the premium. The book is thinner, so a market order eats through levels. And gamma is high — the option's price is moving fast while you're trying to fill — so a half-second of hesitation is a different price. Chasing a breakout with a market order hands the market free money.
Execution is the edge
On a strategy that trades short-dated contracts, the execution logic is not an afterthought — it is the edge. Testing a passive fill when the tape is calm, paying up only when a move genuinely can't be missed, refusing an order when the quote is stale or the spread is blown out — these decisions, made in milliseconds and identically every time, are what separate a backtest from a live P&L.
A short-dated options strategy that ignores its own fills isn't a strategy. It's a backtest that dies on contact with the spread.
Where a system helps
This is exactly the problem a non-discretionary execution tool is built to handle. NoVo reads the spread and the tape and manages the fill mechanically — the same disciplined way, every time, without the hesitation or the chase that costs a human trader the difference. You set the risk; the machine handles the part where short-dated edges are usually lost.