Also, another point is timing of when the bugs are added. If they are added early, I would say a turbid mash would probably be less necessary since there is more sugar that they will be able to eat. The later you pitch the bugs, the more advanced starch reserves you need to feed your bugs.
Mind you, there are varieties of lacto bugs (pedio/lactobacillus) that produce the enzymes to convert starches to sugars, as do most brettanomyces strains to various degrees.
So, all said and done, it comes down to:
1. When do you want to pitch the bugs?
2. How sour do you want it?
3. What end flavors are you going for?
That's where experience comes in. Find your methodology after some experimentation and tastings.
Good luck! Cheers!