Using Lower Duration For Breakeven Spread Analysis

CFA Level III Fixed Income
#1

Schweser says in its Mind Maps (book given out during the 3 day seminar):

If the initial BE spread is positive, Use the higher duration for the more conservative (smaller) spread widening before falling to BE.

If the initial spread is negative, Use the lower duration for the more conservative (larger) spread widening required to rise to BE.

I thought we were supposed to use the higher durarion, always. What is this about using the lower of the two bond durations if the spread is initially negative?

#2

In reality, Schweser is correct about both statements.

However, CFAI will only test instances where BE spread is positive, because it specifically taught us to use the higher duration of the two. So, dont worry about the 2nd statement.