I agree the more aggressive commercial and most importantly healthy yeast will become the big bug on the block (one main reason for doing starters), but we have to remember that there are sugar chains that commercial yeast is not designed to metabolize. Lactobacillious will now through sucrose which sacramyces can't touch. Even when I do a sour mash I'll introduce a controlled strain of lacto to the mashtun and cover it with a sealed lid overnight. I will then finish my sparge and boil to kill the lacto then add my sacrmyces to finish the job. This is commonly known as a kettle sour.
In the lab we normally see lacto and Brett take off with about a four hour lag time.