well, maybe drawing out the time longer means, that they can make more money from the other merchandise that they sell. cuz when an anime ends, unless you're a big fan (which i am of evangelion) you're prolly gonna move on to some other stuff, and buy other merchandise.
or maybe he just draws slow lol. or ... uhh is working on other stuff.
Maybe they are waiting for something. lol
PS: it takes time to create manga books.lol
Aye I understand that... but theres normal manga-ka writing speed... then there's Sadamoto's speed :D
I think it also stems from the fact that Evangelion, the last I remember, runs in an monthy or bi-monthy manga magazine. Can't remember which. Also I heard that he has hiatus's quite often too. Which would explain why he takes so long.
For example, a manga running in a bi-monthy magazine, like Hana to Yume for example, usually takes about a year to form a standard six chapter long manga volume.