That's the other part of the equation, you never know the intention of the buyer/seller and can only speculate. There's a general consensus on some types of orders going thru and the general expectation for those trades(ex. block vs split vs sweep, ITM OTM ATM and long term/short term expirations) where you can make a pretty good assumption but can never know for sure. Spreads are usually followed thru as being spreads and you can make that out as the trades go out together on the short/long legs etc.