Yes, this is the slippage table that we have developed based on actual trading. For example, a single leg will travel 75% of the bid-ask spread to trade while a four-legged iron condor will travel 53%. https://gyazo.com/8f975832052e5ca1bf55754132e32aef
That looks better and is reasonable as a generalization. It makes it difficult for us and it's unfortunate that market makers play games with these values, you can even bid the ask and watch the ask move. Reality really depends on who's on the other side of that trade. Liquidity tends to dry up in volatile market conditions, capturing desperate traders who are otherwise trapped in their position