This article deals with the effectiveness of leveling both Class Enhancement and Class Specialization.
Assuming that the class specialty is of 4% of something (2 classes have this, but it is an approximate average between 3%, 5 classes, and 5%, 11 classes) this table will show you how much experience is required for the quickest way to get a 1% or greater gain from combining Class Enhancement and Class Specialization as opposed to leveling either Class Enhancement or Class Specialization explicitly for a gain.
| Specialty | CE | CS | Cumulative Exp |
| 4% | 0 | 0 | 0 |
| 5% | 50 | 0 | 2.6*10^7 |
| 5% | 0 | 25 | 4.8*10^6 |
| 5% | 16 | 16 | 1.9*10^6 |
| 6% | 100 | 0 | 2.6*10^8 |
| 6% | 0 | 50 | 4.3*10^7 |
| 6% | 33 | 29 | 1.2*10^7 |
| 7% | 100 | 17 | 2.6*10^8 |
| 7% | 0 | 75 | 1.7*10^8 |
| 7% | 45 | 43 | 4.0*10^7 |
| 8% | 100 | 34 | 2.7*10^8 |
| 8% | 0 | 100 | 5.2*10^8 |
| 8% | 57 | 56 | 9.3*10^7 |
| 9% | 100 | 50 | 3.0*10^8 |
| 9% | 25 | 100 | 5.2*10^8 |
| 9% | 68 | 68 | 1.8*10^8 |
| 10% | 100 | 67 | 3.8*10^8 |
| 10% | 50 | 100 | 5.4*10^8 |
| 10% | 81 | 78 | 3.2*10^8 |
| 11% | 100 | 84 | 5.3*10^8 |
| 11% | 75 | 100 | 6.1*10^8 |
| 11% | 96 | 86 | 5.1*10^8 |
| 12% | 100 | 100 | 7.8*10^8 |
For those who wish to check my math, the ExpLevels article has all experience levels listed. Each of the totals on the right of this table is simply a running total of experience from both skills. The formula used to calculate when a combination of skills reaches each 1% mark, the following equation is used: (1 + CE * .005) * (1 + CS * .01) * S, where CE is the level of Class Enhancement, CS is the level of Class Specialization, and S is the particular specialty being tested (in this case 4%). This equation yields the effective specialization per level of either Class Enhancement or Class Specialization.
In summary, the fastest way possible to get a qualitative result is to level both skills simultaneously.