To give an example of how it works, the current system chooses 3 IVs at random, each from a different stat, and passes it to the child.
Code:
Parent 1: [b]31[/b]/16/24/05/[b]31[/b]/13
Parent 2: 17/10/26/[b]17[/b]/08/31
Child: [b]31[/b]/xx/xx/[b]17[/b]/[b]31[/b]/xx
Destiny Knot will do the same, except it chooses from 5 stats instead of 3:
Code:
Parent 1: [b]31[/b]/16/24/05/[b]31[/b]/13
Parent 2: 17/10/[b]26[/b]/[b]17[/b]/08/[b]31[/b]
Child: [b]31[/b]/xx/[b]26[/b]/[b]17[/b]/[b]31[/b]/[b]31[/b]
So yes, there is a chance of not getting the spread you want, due to how the process works. There's still work to be done, but it definitely cuts down breeding time if both parents have good IVs in different stats.