The key parameter is mining-diversity, which controls the rules regarding how many miners must participate in a blockchain in order to make it valid. For production we recommend setting this above 0.5.
The mining-turnover parameter is designed to help with reducing forks but it is not a consensus rule and not a source of security for the network. As stated on the blockchain parameters page: A value of 0.0 prefers a pure round robin scheme between an automatically-discovered subset of the addresses with mine permissions, with others stepping in only if one fails. A value of 1.0 prefers pure random block creation between these addresses. Intermediate values set the balance between these two behaviors. Lower values reduce the number of forks, making the blockchain more efficient, but increase the level of validator concentration.