Recently, discussion of "maximize at 16" versus "maximize Deceptive Attack" was going on. Douglas Cole even ran the numbers on efficient use of raw skill and criticals vs. Deceptive Attack.
But there is an easy way to make sure that using Deceptive Attack isn't a strangely exact science.
GURPS Basic Set, p. 370, has a simple suggestion for making Deceptive Attack less of a dial-the-perfect-odds option. It suggests fixing Deceptive Attack at -4 to hit, -2 to the defender's active defenses. It's nominally to speed play.
But it also has a marked effect on fights. You can't adjust your Deceptive Attack level to either get the most you can while still hitting the "perfect" odds to get through defenses, or while staying at skill 16 to maximize critical hits and minimize critical misses. Still, it might be worth having two levels of Deceptive Attack. The following is an (as yet untested) optional rule.
Deceptive Attack may be performed at either of two levels. The first level (Deceptive Attack) is -4 to hit, but gives your opponent a -2 to any defenses against your attack, should it hit. The second level (Very Deceptive Attack) is -8 to hit, but gives your opponent a -4 to any defenses.
Optionally, GMs may wish to remove the skill minimum, and allow anyone to attempt a Deceptive Attack or Very Deceptive Attack. It's unlikely to succeed unless the attacker's skill is high.
Why -8? A variety of reasons. One is the Task Difficulty Modifier table, which caps out at -10. So -10 would be the theoretical max, and since -8 is double the penalty of the first fixed level of Deceptive Attack.
This would also mean, for highly skilled fighters, that aiming for specific locations or using Rapid Strikes or techniques at default would be more common. You would cap out Deceptive Attack at -8/-4, so you'd have some play beyond that to spend on techniques and hit location penalties. This would also be true if you didn't tier the Deceptive Attack, and just stayed with the single fixed level. It would certainly speed play on the tabletop, and it would limit the precision min-maxing you get with a fully flexible Deceptive Attack.