If working hard was important, I'd trade a 12:30 volume spike (which doesn't exist). Being the smart worker I am, I trade the 2:30 spike. Hard workers come back from lunch early. To the extent that harder workers taker shorter lunches, this should serve as a good proxy for hard vs. smart.
I'd also be looking at a reporting bias on this one based on what I presume would be a high correlation with Type-A personalities and visibility as a trader (i.e. more likely to seek publicity and more likely to be a workaholic). Academia is not supportive of this also correlating with success. So the most visible successes and most visible failures will be those working hardest. (I have no data to support this--except the Type-A vs B and success--but it's something I suspect having worked with statistical samplings my entire professional life).
Edit: Or another example, when it hits the fan, spreads widen like the Hudson, you're in a full-blown panic looking at a 20% draw-down for the day, what do you do? Busy work pushing buttons? Close your computer and walk away? Steele your nerves and watch? Pull out your panic checklist you made during 15 mins of well considered clarity to put in place when you have 4 hours of pain and panic? Not to say there's a right or wrong answer here, but 'hard' work will probably work against you on a day like that.
In those scenarios, what if the hard worker instead had backtested all of the situations and would make a more informed decision. A simply smart worker might figure out everything on the spot because you know...he's that smart.