So, the first two virtues of wisdom and courage are needed to recognize and accept the call to adventure. Once the call is accepted, then the individual is transported into the adventure.
The one goal of the adventure is to capture the boon or gift for society that was the reason for the quest in the first place. As Campbell teaches, the virtue of moderation or temperance is needed to combat the many temptations that will be encountered in the quest for the boon.
I don’t think that the virtue of moderation is needed before accepting the call to adventure, but it doesn’t hurt. Also, without moderation, the individual will most likely not endure the adventure and will return back to the everyday world with the knowledge that the adventure is lost, as is any chance for happiness. How many times have we heard of those who inherit large sums of money, or a family business, or even win the lottery, only to squander the newly-aquired wealth. Soon, the individual is left with nothing and no chance of ever returning to wonders of the adventure.
Also, Campbell teaches that adventurer may not have had enough exposure to risks, and is not strong enough to withstand the forces that must be battled to capture the boon. This failure is not due to a lack of moderation but a lack of proper training and preparation. In this case, the individual also returns to the everyday world but with the understanding that in the future a new adventure may come along. The individual still has the wisdom and courage to recognize and accept the new call, and hopefully the moderation to avoid temptations, but may need to engage in additional exposure activities to gain the proper training for future battles.
Of course, there are those who do have the proper training and preparation but lack the virtues. In this case, these individuals will never recognize or have the courage to enter into the adventure; they will be denied happiness in the future.