I just had a realization:
So except for certain edge cases, you basically never want to use Marksmanship on any ship which is only attacking once per turn. The card is too expensive to lock you into an offensive focus, and to get the most value out of it you need to be using it as your action pretty regularly- which means not making defensive actions, which means you're letting naked green dice determine if your ship lives or dies. FFG seems to have realized this, and so created Calculation.
The value of Marksmanship changes a bit when you're making 2 attacks per round. Instead of paying 3 points to take an action that flips a single focus into a crit, you're taking an action which lets you effectively focus two shots in one round. That's useful if you're Corran Horn, or a ship with a TLT. Maybe not worth the opportunity cost, but certainly makes good use out of the 3 points.
Now let me throw this at you:
"Omega Leader" (21)
Juke (2)
Comm Relay (3)
Colonel Vessery (35)
Marksmanship (3)
Tractor Beam (1)
TIE/D (0)
Darth Vader (29)
Juke (2)
Advanced Targeting Computer (1)
Stealth Device (3)
TIE/x1 (0)
Total: 100
View in Yet Another Squad Builder
Take a look at Vessery there. He's attacking twice per round. And if he's doing it right, he has _focused and target locked attacks_ both times.
The list above is just a quick idea I knocked together. Marksmanship isn't a Vessery-only EPT, BTW. I'm going to postulate that it's now a good EPT on _any_ Defender rockin the TIE/D title. There may be others, but I think Marksmanship has found a useful place in many more lists than it previously had.