The most important fact about any gaming system is information when, how often and what their customers win. The software companies have figured out what setting works better with their software and plan to keep the winning percentages with the algorithm they have already identified as the most successful.
Many gaming systems do not still have an option for that. Sometimes, in really extreme situations, the winning percentage can be modified. But this applies to the situations when, for example, a store has had a hold outside of the expected range over a 2-3 month period.