If I recall, your jails/petties for the day is a contributing factor. I'm not positive though. 

As he sat around he read the news he the contacted DocHoliday and reported that he too had the same problem wondering if it was just because those with lower status blended in better because they were less infamous or because Don's and Godfather's were just too experienced whatever the problem was it confused him.

Everything we do is impacted in some way by randomness. Organized Crimes are no different; regardless of how many crimes and jails you have done, no matter your rank or the rank(s) of your comrades in crime, there is always the chance to succeed or fail. Nothing is ever 100% given. One would think that having more high ranking mafiosi would be beneficial, but that is not always the case, especially if they have been less criminally active in recent days. A thug trying to make their bones may have more recent actions than a don with little to prove. Perhaps that is why you've noticed better success with thugs.

 The Dodo bird worked this out for me as we were all dancing to dry off from the flood.  He said you need a mix of high ranked mobsters and low ranked mobsters (associates). This combination gives you better overall success on organized crimes. The higher ranked mobsters give you the experience needed provided they have done the work. While the ones below Made help take some heat off from the authorities. This is because they are less known.