How much boarding to reliably board once?

[Keukotis]

In my current ship, I rely on closing in fast and boarding to win. I have some range change boosts, lots of Pilot, and one Boarding Assault System 4. I regularly score boarding rolls of three or four times the enemy's roll when fighting human ships (Challenging difficulty), and I never come close to failing to board xenos. But I rarely get the engine or Captain. I often win battles by just killing the entire enemy crew after several boardings. Having this high of boarding seems to be a waste.

What I'm wondering is if I should replace the BAS4 or add another?

I can easily board without it. If doubling down would actually make me reliably get engine/Captain, that would be worthwhile. Otherwise I may just scrap it for a Pilot Assist Module or something.

Is there a point where boarding is so high that you can expect to get engine/Captain frequently?

[Keukotis]

I went ahead and tested it. I slapped three more BAS3s on my ship and used Perfected Approach and Single-Minded Strike in battle. I was commonly getting rolls 5-8 times higher than the enemy. I never got engine. I got the captain once against a pirate, and only after five boardings with a roll of 122 vs 11 (they were weakened a lot) on that last one.

Boarding above what is needed to reliably succeed appears to be worthless. The Wiki claims getting a higher roll improves your chance of engine/captain, or at least something valuable. I am just not seeing that, and for this testing I stacked boarding well above what would be reasonable. I usually just got Officers Quarters, Armored bulkheads, or something else unimportant.