Depending on who you read in the bridge world there seems to be two schools of thought when it comes to adding shortage points to your HCPs once a trump fit has been found. Some authors state that : Void = 5 points, Singleton = 3 points, Doubleton = 1 point, whlle others state: Void = 3 points, Singleton = 2 points and Doubleton = 1 point. Why the difference in opinion for the evaluation of a void and which is correct?
I think that the reason you have not found expert consensus is that you should not really be thinking about points in this situation. It is more helpful to think of the usefulness of the shortage. Is its value in being able to control a suit, or to generate tricks by ruffing in the short hand? Is it facing duplicated values in partner's hand?
But if you prefer to think of it in terms of points, a rule of thumb that may be helpful is one that I have read recently: when supporting partner's suit, add as many points for a void as you have trumps in your hand.
In the 2009 edition of his GUIDE TO BETTER ACOL BRIDGE, Ron Klinger echoes the sentiments of many (most?) experts who teach. He makes the following recommendation for those who like to count points:
"After your side has opened, hand valuation for later bidding is based on HCP plus Length Points (LP) when no trump fit had been located, and HCP plus Ruffing Points (RP) when an 8-card or better trump fit exists. The difference arises because of the manner in which tricks are won."
Klinger then continues with a description of how to count LP and RP with various hand patterns. In fact, he regards this as fundamental, since this discussion occurs on pages 2 and 3 of the book.
I highly recommend this book to Acol players. It is well-written, albeit sometimes very packed with text, but the accompanying hands are well-conceived and instructive. The only error in the book is on page 66, where the fourth line from the bottom and the second line from the bottom are contradictory. (He wrote to me that he would correct that error in the future.)
Valuing hands once a fit has been found is a difficult area requiring judgment. I would use the Losing Trick Count to supplement my points based valuation of the hand (Ron Klinger has also written: The Modern Losing Trick Count).
But as Daisy has noted the fit with partner's suit is very important. Your void is so much more useful opposite xxx in parner's hand than KJx. This is where splinter bids and other shape showing bids can help your partner to judge the worth of his hand.