When you launch a new product or service you need your sales reps to start calling their customers and prospects on Day One in order to get your initiative off to a fast start.
If reps have doubts about what they are selling or how they are selling it, that fast start can be slowed or even permanently sidetracked. On the other hand, if your sales team has confidence in the sales process and the sales content that they will use to execute your launch, it will shorten the learning curve and they will be more likely to enthusiastically make those all important first customer calls.