There is no possibility of infecting your systems with microbes and having off or failed batches due to unwanted bacteria in beer batches.
Kettle souring can add 24-72 hours to the fermentation time of a batch of beer. Using a souring blend only adds the time to add the blend – normally only minutes and can be done anytime from the kettle to keg.
A batch of beer can be split and produced as both a sour beer and a non-soured beer.
Off batches may have flavors that are not acceptable in a non-sour beer but are acceptable in a sour beer.
When compared to the cost of overnighting a strain of microbes and the time it takes to sour the batch, the cost of the souring blend is very inexpensive.
When setting up formulations, the testing and flavoring can be done at the pitcher or bucket level with no waiting for a full fermentation batch. This means the level of sour can be easily changed just by adding to what you are tasting.
The microbes used to sour beers can vary due to growth rates by small changes in temperature or other parameters in the wort for making beer; microbes also mutate over time and generations. Either of these can cause flavor changes that are often unacceptable. The addition of a souring blend is extremely consistent and repeatable.