Ok, so I did a test.
I shot one roll of a still life consisting of a few items sitting on my kitchen table: two flashes (black with details), a bag of coffee (green bag), along with a couple of white coffee cups, a steel reel, and my computer mouse (black) and napkin (white)
I shot sequences at 400, 320, 250, 200 blank blank blank, 400, 320, 250, 200, blank blank blank...etc.
I split the roll in half and developed one half at the Ilford recommended time of 11 minutes, and the other half at the Massive Dev time of 13 minutes.
Then I made a contact sheet for minimum time to get max black. (which was 18 seconds) at grade 2
I then made (without moving anything) four 8x10's, (the ones box speed and ones at 200) all printing for the same 18 seconds and grade 2. Here are the results:
Exposed at 400 and dev'd for 11 seconds:
Shadows / blacks are a bit weak but the highlights look good with just enough detail where it needs to be.
Exposed at 200 and dev'd for 11 seconds:
Shadows / blacks are a bit weak and the highlights are void of all of the detail that they should have.
Exposed at 400 and dev'd for 13 seconds:
Shadows / Blacks are nice and strong and highlights are good with just enough detail where it needs to be.
Exposed at 200 and dev'd for 13 seconds:
Shadows / Blacks are nice and strong but highlights are void of all of the detail that they should have.
Now I know why the massive dev chart said 13 seconds, clearly that time produced the best print using the minimum time for max black for my paper.
I do think that my earlier negs were so far out of the ball park that I did something wrong, I'm guessing it was a significant math error. Those negs weren't even in the ball park.