This mod changes the major, minor, and specialization ratios so that all skills increase equally, and all skill increases count towards leveling. All skill increase 25% faster, and it requires 25 skill increases per level. It makes it so that choosing a major skill only adds +20 to that skill, it doesn't affect whether it counts towards, leveling or how fast it levels. Class specialization is ignored.

With default settings, major skills require 60% as much skill experience to increase, and specialization skills require 75%, and they stack multiplicatively. Instead of simply dividing the bonus by three, I scaled it by 7 divided by 18. Your character usually never uses both armor skills, and usually uses only one strength/melee skill. The number of skill increases required per level is similarly scaled up by 18 / 7, which gives 25. The 25 settings is recommended if your character is a generalist that uses all of their skills, except for the aforementioned. If your character only uses two-thirds of their skills, the 20-30 settings is recommended. This makes all skills require 70% as much experience to increase, compared to minor skills, and requires 20 skill increases per level.

Note that the default coefficient for minor skills is 1.25, so the actual coefficients are 0.9375 for the 25 version, and 0.875 for the 20-30 version.

It has just one simple script, that uses your "skill increases" stat and current level to determine leveling progress. It sets  SetPCMajorSkillUps and leveling happens normally. It does not affect how attribute bonuses are calculated. It is compatible with "All +5 Attribute Modifiers", for example. As far as I can tell, it is hard-coded that all skills start at 5, and get +20 for being a major skill. I couldn't find a game setting that changes that. By default, all races also have a total of +45 skill bonuses, but it looks up the race skill bonuses, so that it still adds up if this is modified.