I dont now if I phrased it correctly...It is possible that kicks/MT and punches/boxing have the same rates; boxing seems to go up rapidly by training punches, however, they dont have the same effect on MT. Maybe I should have said it's easier to train up boxing and BJJ than wrestling (and probably MT) due to certain primaries providing a nice boost.
Fighter above started out at 1-1-12-1; gained only + in wrestling, 7 in BJJ through def grappling. You can see boxing go up more than MT with striking training.
What you should have said was what listerman described:
You trained secondaries that focused more on one primary then the other. Had you started with defensive grappling instead of TDD and trained the TDD, then you would have gained more in wrestling and basically nothing in BJJ. It would look more like exceptional++ wrestling and useless BJJ.
Basically if you look at the chart listerman posted, you can see roughly how the points that will be gained to the primes during secondary training it go towards those primes.
Example 1: say ground and pound lists both primes wrestling and bjj as the same so you will roughly gain the same towards both primes the same. So if you gain 20 points towards primes, then roughly half go to both. That doesn't take into consideration on a skill difference between the two primes as obviously a unless and wonderful prime are going to gain a different rates.
Example 2: sub offense is mostly all BJJ and very little wrestling so if you gain 20 points to primes, then maybe 15 go to BJJ and only 5 goes to wrestling.
If the chart list needing both, then you can probably guess it is close to 50/50. If it says one and another prime is secondary, then a guess of 75/25 is likely and if it says another is minor then it could be something like 80/20 to 90/10. Again guess's to a certain degree, but logical.
But I think aylib was more meaning in his original post that sparring isn't overly required to get higher primes, least until later in age. Which I totally agree, beside sparring to reset depop tickers.