If you have ever read from this space or others how to play your hands in the game of blackjack, whether it is online or in a land-based environment, you are always told about what to do for every situation where you are dealt the first two cards and have to make a decision against the dealer's upcard. And there is no question that if you learn all of those components of the "Basic Strategy" properly, you are going to be playing the closest thing to a break-even game as you possibly can, and the closes thing to a winning game without counting cards.
When you look at the lost of playing decisions, or a chart that is color-coded, you are seeing al those situations in front of you that you should know like second nature. But for those players who may be new to this kind of thing, they may get crossed up here or there. A perfect example - when they make the decision that the chart tells them to make, yet there are further decisions that have to be made. This happens when you have taken a hit, for instance, and are still not holding a "pat" hand (17 through 21) against the dealer's "pat" upcard (7 through Ace).
Okay, here is an example to ponder; you are dealt a two-card 13 against a dealer's upcard of ten, which requires you to hit, as per the Basic Strategy. So you hit, and get a two, which brings your total up to 15. Now what? Does the Basic Strategy tell you specifically what to do when that third card comes in and you're still not finished? Well, yes and no. While it does not say anything specifically about when you have a three-card hand of any particular value, the numbers for hand values that you see in the Basic Strategy chart are numbers for the HANDS, period.
That means if you have a three-card 15, you have a 15, period. And if the dealer has the ten, or a ten-value card, you simply look at that blackjack strategy chart, or refer to the one you hopefully have memorized already, and make an additional HIt to the hand. So what is the lesson here? Well, when you encounter a multi-card hand, simply plug that value into the Basic Strategy you have learned and just go from there. That is absolutely the sound way to go.