foreigner said:
what time zone is this indicator ideally suited to?
Human time zones. Yes, definitely human time zones. Although, many of them still don't get it.
Sorry, couldn't resist.
The answer is
any and all. The tool is generic and works in any liquid market with enough participants so it works just fine no matter which server time window is peered through.
People are people. It is their collective behaviour that is mapped by price action charts. Sure, the lines may differ a little in their position if one adopts a different measurement of daily cycle time, but this is inconsequential.
There is no ideal day hidden somewhere in the passage of 24 hour time cycles, there is no magic. Individuals may well become accustomed to or more comfortable with one particular viewpoint and that is fine. It doesn't make theirs or mine any better or worse than another.
I personally think that the most sensible perspective is the one adopted by MetaQuotes, which houses (or "home-bases") their servers in UTC+2 or 3 (depending on DST). This makes New York close the end of the natural day cycle and generates 5 full trading days per week, with no little annoying Sunday trading to mess things up.
The other common approach is to base the cycle on UTC. This seems to me to offer no benefits and some real costs but it remains popular with many brokers nevertheless. Mind you, brokers have been known to wise up and make the switch. Global Prime is one example, see here: http://www.forexfactory.com/showthread.php?t=439997
But to get back to your question, I can assure you that the pivot tool will detect and project meaningful support and resistance levels no matter what time your quotes server is set to. Thinking that one time slice is better than another is a version of the grass is greener syndrome in many cases. Then again, perhaps having slight variation in levels by having substantial numbers of traders "trapped" in slightly offset "days" helps to keep markets moving.
I will put some horizontal line tools together in a thread. You may find something useful in there.