No one knows what the future will hold, but there's a concept called "sensitivity analysis." A static sales (or growth) forecast may make your business look profitable, but a very small difference in sales could make a big difference in whether your business is profitable. Same thing with projected growth.
Some parts of the business plan might be relatively robust, for instance it's common for construction or plant costs to end up being much larger than anticipated, but the company is still profitable even with twice the start-up costs.
There's no "one size fits all" solution, but I've seen a lot of business plans that just create one static projection of sales, and the whole thing would fall apart if they don't hit their overly-optimistic numbers. That's not to say you should be as conservative as possible, because risk = reward. The safest thing is to not open a brewery at all, but that's not always the best solution.