Yes, you're right--I didn't mean to say that all Ns are good at long-term planning nor that all Ss are bad at it. You're right--what we're seeing in this thread kills that hypothesis. So I have to ask about the study itself.
I have to agree with the original study. I believe that the flaw here is more likely to come from;
1) The casual typing here is probably about 60% accurate (this is guesstimated, naturally).
2) Forum regulars will be biased towards different specific traits than the general population.
3) We tend to measure open ended questions in terms of ability, not preference. For example, if I was to answer the question, I'd say that I plan 3-5 years in advance. However, all my spreadsheets (somewhere in excess of hundreds) project at least 30 years into the future, or derive an immediate solution to my assumptions (rent vs buy). Different people measure time and plans in different ways - I don't have a career plan, but I have a retirement plan (big empty 30 year space

). I was planning my wedding for a couple of years whereas my GF (INTJ) hasn't even thought about it. But ask me to show you anything tangible and I couldn't show you a single tangible wedding plan... my GF could, despite saying she hasn't planned a thing. To her it's not a plan if it isn't fixed.
For example, in the N thing...
I project into the distant future - early on in my spreadsheet fun I was projecting beyond my natural lifespan without even realising it. To me they were just models. They were a way of understanding how things work, and for me, that meant into the distant future. If you sit me down and talk to me about where things are going I tend to expand into more and more uncertainty, building theories way way off into the future.
I'm extremely strong N (and in terms of FFM, open - which also has a time horizon component). Compare this to my GF who isn't that strong of an N, who rarely plans beyond the next few events. However, when she plans, she *plans*.
It's about the concept of time. Ns prefer seeing how things relate, and in theory, they relate things into the far future. Ss tend to see how things are and aren't as comfortable projecting into the future. The corollary is that Ns tend to project in to the future accurately, relatively speaking, but still extremely badly. They do so despite lacking sufficient information to make an accurate guess. Ss deal with the realities as they are now, and as such, are rarely wrong but simply don't risk being wrong by seeing too far into the future. How this manifests itself in planning differs. INTJs, for example, are well known to be project planners - but if you take project plans from an INTJ and an ISTJ, there is a bias towards the INTJ building lag time into the project, always depending on the individual project's needs. ISTJs lag time is almost always identical, and often creates problems further down the path. Their method of planning involves setting the plan according to fixed milestones, not reading into the future to anticipate needs. When individuals operate outside their normal time horizons, they tend to either rely on outside help or extremely static "I've done it so shut up" kinds of plans. It's pretty common in finance, where the majority of people just want a plan, not to work through it. A common problem with dealing with SJs is that they hate the concept of assumptions - rate of return is always assumed, etc. Variance is a big issue with them! With SPs, for example, they simply want to make sure it is taken care of - they rarely care what the assumptions are, they just accept that they are there. Yet, they are the same ones that will call you if the one year return is bad.
In a similar way, INTJs vs INTPs may have the same time horizon but vastly different views on how to plan. The INTP will often have multiple views on how to build a schedule. When I built a schedule for an ENTP project manager and handed over to a SJ manager, the immediate comment was that list of schedule impacts was simply too large - and not relevent.
In a similar way, my GF just called me to ask if I had this Friday off. At work, the SJ boss would prefer not booking time off too far into the future because it's her job to make sure that there are no projects that will be impacted - makes sense. My GF, however, didn't want to make plans until I had the time off. Both operate off the same basic view on planning - variance is evil. The time horizon isn't correlated to that.
[/rambling]
Anyway, this is something that has always interested me... From what I know, the general conclusion is that there is a correlation between N and time horizons, the planning bit was more about how far you think into the future - and lastly, I believe the research shows that the correlation is largely from clumping - but the spread is still fairly large. Not the strongest correlation, IOW.