I understand the question, I think. The tough thing is that trades over the next brief time are random, or appear so. So, just as when a stock is $10.00 bid / $10.05 ask, if you place an order below the ask, a tick down in price may get you a fill, or if the next trades are flat to higher, you can find the close at $10.50, and no fill (order execution).

This process is no different for options than for stocks.

When I want to trade options, I make sure the strike has decent volume, and enter a market order.

I understand the question, I think. The tough thing is that trades over the next brief time are random, or appear so. So, just as when a stock is $10.00 bid / $10.05 ask, if you place an order below the ask, a tick down in price may get you a fill, or if the next trades are flat to higher, you might see the close at $10.50, and no fill as it never went down to your limit.

This process is no different for options than for stocks.

When I want to trade options, I make sure the strike has decent volume, and enter a market order.

Edit - I reworded a bit to clarify. The Black–Scholes is a model, not a rigid equation. Say I discover an option that's underpriced, but it trades under right until it expires. It's not like there's a reversion to the mean that will occur. There are some very sophisticated traders who use these tools to trade in some very high volumes, for them, it may produce results. For the small trader you need to know why you want to buy a stock or its option and not worry about the last $0.25 of its price.

I understand the question, I think. The tough thing is that trades over the next brief time are random, or appear so. So, just as when a stock is $10.00 bid / $10.05 ask, if you place an order below the ask, a tick down in price may get you a fill, or if the next trades are flat to higher, you can fine the close at $10.50, and no fill (order execution).

This process is no different for options than for stocks.

When I want to buy/sell options, I make sure the strike has decent volume, and enter a market order.

I understand the question, I think. The tough thing is that trades over the next brief time are random, or appear so. So, just as when a stock is $10.00 bid / $10.05 ask, if you place an order below the ask, a tick down in price may get you a fill, or if the next trades are flat to higher, you can find the close at $10.50, and no fill (order execution).

This process is no different for options than for stocks.

When I want to trade options, I make sure the strike has decent volume, and enter a market order.