For me, having the ability to use Instant Boarding unrestricted does make the game more enjoyable. Normally sailing in to board properly is all part of the game and that's fine, but occasionally I sail up to the ship, pass alongside it, never get the boarding icon, continue past it, and use Instant Board to trigger a boarding which should have happened anyway. (Well, I think so anyway.

) Or I've found an enemy on the worldmap, gone to sailing mode to attack, and found it's one small ship which I'm not letting get away but which isn't worth all the effort of a proper boarding - just Instant Board, get it out of the way, then return to World Map and look for something more interesting. Or I've found something more interesting, then:
"Six enemy ships left - what's the time? $#&£! Board, board, board, board, board, board, back to worldmap, save, done, time for bed!"
