Why is Hebrew divided only into 12 levels only?
I'm studying Hungarian and German, and while I've completed learning the entire Hebrew course and which peaks at level 12, I haven't even reached %15 of the entire course and I'm already in level 9, isn't it because the course is chopped up into smaller pieces that determine the level points? I personally prefer smaller the levels to be smaller, so you progress is more often, which is a pretty neat motivator, but the Hebrew course should either be divided better, or each course should say Level 12/12 etc., to determine how many levels there are in total.
I'm not sure what you mean by the levels being divided, but I'll answer best I can about what I know.
Most people don't finish their tree/course before reaching the maximum level (25). In fact, if you haven't reviewed any of the material, it's more likely you'll complete the course at level 12 to level 15 on average, because you're not getting the extra experience points from review. I finished my Spanish course at level 16. I'm at level 19 now because I have been reviewing a lot. That's still very far from level 25.
The way Duolingo's point system works is that when you complete the lesson or review, you gain 10xp (experience points). For each level, you need a specific amount of XP. You need 60xp to get to level 2, but you need 15,000 xp to reach level 20 and 30,000xp to reach level 25. So basically, to reach the maximum level, you have to do the course several times over. Some people will cheat this system by doing only the basic lessons over and over until they reach level 25, not even finishing the course. But the reason that Duolingo has this system is to encourage people to repeat lessons in order to memorize the material.