How far ahead is far?

Since i came to Japan i have seen alot of people with schedule planner and a small book to put all that in. I was always wondering how usefull it is since im more a day to day person even though i plan thing ahead of time by a far marging usually. Yesterday, i have been confronted with the mesurement of time with cultural distortion. One of my Japanese friend came to ask me when i was leaving because i might not be able to seen him again. This was not a big surprise but when he went to ask another person of my circle, I was. He had half the next year meetings all planned out in this small book with everything else he already has plan for that half a year. I was greatly impressed as sometimes i ask people or I am asked what i do in the weekend and I dont know sometimes until the friday night. Seems that it is the same for everyone here as Japanese have a long term view on things and this reflect to the "everyday day" planning that seems to expend to half years. I wonder how many people know what tey will do on the 15 of Septembre already which is part of the "daily" life schedule...