We all know that in Oblivion, and I'm assuming in Morrowind as well even though I never played it, you could just spam that conjuration / restoration / alteration / mysticism / illusion spell over and over until they are at level 100. This is a terrible thing! This is basically just cheating. Change it so that each of those skills can only level up when it actually does something. So for example, restoration wouldn't level up until it's healed X amount of health, conjuration wouldn't level up until your conjured creatures have done X amount of damage, etc etc.
I don't know if this has already been mentioned before or even covered, hopefully it has and it will be changed.
The conjouration one doesn't make any sense. Theoretically, creatures can be conjoured for many purposes other than fighting. The act of successfully conjouring them and not having them run haywire on you would, in and of itself, increase your proficeincy and mastery of the craft.
The health one makes some sense, but one could still "spam" it if one wanted to. Just keep jumping off a large rock or into a camp fire, and then heal, heal, heal.
If people want to repeatedly cast, and categorize it under "intense study and application course" let them. Believe it or not, there are imaginative ways for people to work such things into their stories.
"the great mage, Vandilaid Laythylas, cast himself from the starboard bow, into the waves of The Abaccean Sea, and all thought him surely perished and gone. . . but amidst the turbulent waves, the penetrating cold and the majestic, deadly creatures of The Deep, he survived. At the bottom of the sea, he lingered, as one in a trance, repeatedly casting enchantments of alteration, of water breathing, and of shielding to protect him from cold, and from the fearful jaws of lamai and weresharks. . . and many days later, he emerged from the depths, washed up upon the shores of High Rock, and become one of the greatest masters of the school of Alteration that this 4th era has yet known."
There are all sorts of ways to play an RPG, to one's liking. If you think spamming is a cheat (it really isn't at all, for many reasons, but if you really feel that way), don't do it. Cast only when required, level more slowly, and be content.