Life In 19x19

You missed out the most important question:
Is this a rematch where I lost the first game?
Yes => Kill.

Out of curiosity I checked Sakata's book, Ishi no Semekata (How to Attack). OC, Sakata's selection of examples is not random, but they do reflect what he meant by "attack". I decided beforehand to leave out the examples in the last chapter, How to kill, because I thought that it might be biased against large groups. There are 22 examples in the first two chapters, which are about attacking single groups. There are 18 examples in the next two chapters, which are about attacking more than one group, leaning attacks and splitting (I prefer to say twining) attacks. I figured that counting the largest groups in multiple group attacks was fair.

What is a large group is not all that clear. Stone count is an indication, as is how spread out the group is. There were a number medium sized groups with 10 - 13 stones that I did not consider large, but others might consider at least some of them to be large. Two of these were in the 22 examples in the first two chapters. I decided to give the benefit of the doubt to one of those and counted it as large. One out of 22 fits with my sense that attacking large groups is seldom indicated.

The 18 examples of multiple attacks contained two with large groups, one with 19 stones and one with 15 stones. There were 5 examples with medium sized groups, and I decided to give the benefit of the doubt to two of those and count them as large. Four out of 18 attacks involving largish groups does not fit my sense of seldom.

So now I would say this:

You should seldom attack largish groups, unless you can also attack another group at the same time.

The dual attack makes the attack on the largish group more potent.