I just found this post from the TWIPY awards.
I wanted to congratulate McSquid and to thank him for
fallowing a target pinball rule that I have found always makes a good pinball.
History: I have found that sense Williams Black Knight, that a good pinball
--- layout has a 3-4-12 rule... or 4-3-12.
Your pinball layout fallows the later.
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1) The pinball playfield has 5 clusters of targets, in 3 position on the playfield.
--- That is a total of 15 primary targets to hit.
--- and a bit of extra room to add more stuff to sweeten the setup...
Again, congratulation on the TWIPY award and having a neat pinball layout.

Simple multiplication... Williams Black knight has:
1) a 3 bank of drop targets...
2) multiply by the dispersion on the playfield...
[ Black Knight has 4 banks of drop targets dispersed on the playfield ]
3) equals the total...
-- Black Knight has a 3 bank D/T X 4 locations on the playfield = 12 targets to hit.
4) So Black Knight is a classic 3-4-12 layout.
OR a layout design can flip the ratio 4x3 = 12
The layout that you have fallows the 4-3-12 formula.
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Look at the target setups on these two playfields, they meet the minimal formula and
where able to add a bit more....
A) High Speed 3-4-12
B) Torpedo Alley 3-4-12
In all, it is just my quirky target terminology/formula I realized many years ago.

The formula is for the bare minimal threshold.
Once a playfield meets the threshold the rest is just extra.
Another example is:
Premier/Gottlieb Hollywood Heat... 3-4-12.
Side note:
"High Speed has 5 groups of 3 targets" Answer; true. [ layout target threshold achieved + extra ]
"(though two of these groups aren't "collectible", they're just hit-whichever-one-is-lit)"
Answer; This comment is a rules comment, not a target layout.
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Like I said above: "it is just my quirky target terminology/formula I realized many years ago".
Congratulation McSquid on your achievement.