Yeah, HOWEVER, try to get 15 skill increases in three diffrent skills with diffrent primary attributes.
It's rather easy, but you have to know how to do it.
Theoretically, this should give you +5 in three attributes, but it DOSEN'T, at least not in my experience.
I would disagree, as I've done it many times. Apparently you are not doing it correctly.
The best way to do it is to create a class where your class skills are skills you only increase when you
choose too. In other words, skills like armorer, acrobatics, hand to hand, speechcraft, etc. These are all skills that in order to increase them you have to do specific actions to increase them. In other words you will be picking class skills that you have no intention of using, or if you do it'll be very rarely.
If your character mainly wants to use light armor and a blade, than you would
not take those skills as your class skills. Insteal you would take heavy armor, and/or blunt or hand to hand. Do not pick class skills that you will use a lot.
My last game I played prior to quitting Oblivion was a game using the above method. I wanted a powerful mage character. I never raised a level until I knew I had a +5 in Intelligence, Willpower, and Endurance. By 8th level my Intelligence was 100, by 9th level my Willpower was 100, and at 12th level my Endurance would have been 100. Note, though it is possible (as I've done it) its also very boring. The game takes longer to play as you are specifically increasing only certain skill levels. Battles though are a lot easier, as even though I was low level my magic was at a very high level. I believe I quit at 10th level as this game became too boring. I can't remember exactly what my class skills were, but I do recall that light armor and blade were two of them. I typically wore heavy armor (to increase endurance) and used magic to fight.
Edit: For those of you who wish to give this type of game a try, I suggest you check out the
Skill Diary mod. This mod keeps track of all increases between levels so that you know exactly what your attribute modification will be prior to leveling. Again, let me note that once you get the notification that you have leveled the counter automatically resets to zero. When you sleep and adjust your level has no bearing on the bonuses.