The FIVE [5] in Card Counting.
In the first edition of "Beat the Dealer" (1962) and in Uston's "Million Dollar Blackjack "The Ace-Five Count" is presented. At a GOOD single deck game with good penetration all one needs to count is the ACES and FIVES to gain a nice edge. This count is otherwise worthless.
Level 2 and level 3 counts ordinarily count the 5 [or the 5 and the 4] with extra weight.
The "effect of removal" is highest for the 5 but the 4 is also very powerful.
Thus, the Hi-Opt II - the strongest (practical) count for hand held games - counts only the 5's and 4's at +2 and the 2,3,6,7 as +1
The covert reason for Level 2 counts is that not only are they more accurate at identifying your advantage, but since surveillance and pit critters and counter catchers ALL use Hi-Lo, you may be seen as playing sloppily when in fact you are playing a stronger game than they know.
Lets say you are playing a nice DD game and using Hi-Opt II [with side-counted Aces] and there is a flood of 2's and 3's depleted and surveillance thinks that you have a plus count but you bet minimally because you don't.
Now, the next deal, you see lots of low cards dealt, but you have reached 75% pen, it is the final hand, but all 8 aces have been played, you leave the table - and they mark you as a non-counter.
You return to the table and on the next shuffle there are no Aces dealt but all the 5's have been dealt. It is the 50% penetration point, Hi-Lo looks like it is neutral or negative. In reality your Hi-Opt II True Count is +16 -- which equates to an advantage shift of 4% You have 2 hands out at your MAX bet, since you now have an e.v. of between +3.6% and +.3.8%, depending on the house rules. You realize that this is double the edge that you require to shove lots of your chips across the felt.
The pit sends over a host to offer you a gourmet dinner and a suite; you act humble and grateful, but you are smiling inwardly basking in the glow of the certain knowledge that you really know what you are doing.
You have arrived.
Think about it!