Quote from dummy-variable:
you're arguments are all very cogent and logical and i don't disagree or have a simple reply.
but let me toss another thought (or half-thought) out. what if the intended position is ultimately the butterfly as riskarb has suggested. the position is legged over time by embracing an unknown but reasonably controllable set of risk factors with the intention to lay those risks off as the market permits or forces. it can be built any number of ways: buy the strangle first, trade the verticals initially, just buy or sell a single leg, etc. but the ultimate goal is the same: own a fly for less cost than current market value.
each individual trade is a discreet negative expectancy event and as you imply can be looked at without regard or memory of what happened previously.
but still the trader has retained these memories and in fact has planned to incorporate them into the ultimate position. so the relationship is now more complex. and indeed the sequence of trades and the history of what happened now has the utmost relevance.
now put a twist on this. say i enter a trade randomly. after sometime the market has moved in one direction or another and any number of variables has changed. yet i have that initial trade and i now have to do something with it. i will seek to either close it or adapt it by incorporating it into a new position based on whatever is available to me now. i may or may not construct a butterfly. but the fact that i didn't have a plan initially does not negate the relevance of the past trade for my decision process. my goal is still the same: own something at a net cost less than current market price. i am not making predictions about the future exactly, i'm employing my skills and experience to set up moves that take advantage of possible scenarios. kind of like a master chess player that plans a move based on mentally rehearsing groups of potential sequences.
maybe this is the definition of trader skill. the ability to adapt to circumstances using vehicles that in isolation are completely random negative expectancy events. it has nothing to do with having an opinion about the future but has everything to do with knowing the dynamics of options and managing their risks.