I agree that opportunity is not a commodity. It is an intangible concept, a convenient word to describe a confluence of choice and circumstance, with the emphasis largely on the latter.
An opportunity must be somehow provided to qualify; perception and acceptance of it then breathe life into the definition. After all what is an opportunity without someone to perceive it? Then, perceived but not accepted, it is merely a missed opportunity. See, I'm in deep trouble already, which is handy as I'm trying to highlight the happy futility of arguing a strict definition.
By provided I do not necessarily imply conscious intent: e.g the opportunity to watch a sunset is not provided deliberately by the Moon going Oi Earth mate shift round a bit I can't take any more Pink Floyd. Nevertheless it is definitely not provided at half past two in the afternoon, unless one is the type who says without irony Yah I'm still on New York time actually, talk to the Slackberry.
Anyway, the purest opportunites tend to be fleeting and potentially beneficial.
If one spots £5 lying in the street the opportunity momentarily arises to pick it up and enrich onself (unless one is an economist who, having seen a beloved law of efficiency roundly disproven, wishes instead to burn it and thus enrich everyone currently holding money by imperceptibly lowering their cost of living). It doesn't arise if one doesn't see the fiver. There would be an opportunity cost incurred if while kneeling down a tenner floated jauntily by - just out of reach - and blew into a river.
Of course I also have a perennial opportunity to scratch my ****, at least until my scalping hand is run over by a four hundred pound bulldozer. Twice. But this would probably not be described as an opportunity except by one with threadworm or a persistent interest in the smell of faeces. Or, god forbid, both. Anyway I need to shut up and get onto Guy Browning about this for his How to column. He would do it much more elegantly.
Emotional traders make decisions which often lead to volume. Emotions can tear through crowds like a bush fire. A fixed time bar highlights this effectively as there will be sudden increased vertical movement for the same horizontal unit. It jumps out like a sore over-leveraged stop loss. Whereas in the same circumstances a volume, tick or range bar just says no worries mate no need to panic I'll just print more frequently to keep things looking calm and orderly. In this case the obvious visual representation of emotion is attenuated, though imho by no means removed. Both these shades of perspective may be useful.
One could rig up a device to take his pulse and then print bars in relation to its frequency. That way when he is being assailed by involuntary heightened emotional response they'll subtly print more quickly, much in the manner of a volume bar, thus avoiding those tall scary candles that might lead to suboptimal primitive responses.
But perhaps he won't truly reap the benefit cause the overall vertical distance between a bunch of them will still be changing on the screen so, erm, fast.
Whatever type of bar a day trader employs in a conventional charting package there is no escaping the fact that (vertical - and it is invariably so) price movement will naturally be viewed with reference to time even if the bar in question or the x-axis furiously denies it. The human subconscious just can't help it. Still, it makes a market tick. Sorry none of the above is new or relevant.
PS Stamp out grafitti on toilet walls: sign a partition now. Oh dear.