Thanks for your reply.

It just seems to me that after all these years (decades really)
BIAB does not look ahead and analyze a chord progression, but rather simply looks ahead chord by chord.

Why jump up and down octaves for three consecutive notes when it is not necessary?

C, DOWN to low E, UP an octave to D, then DOWN to F !!!

If BIAB looked ahead and saw the D and F, surely it would have realized that going UP to the E instead of DOWN would have made a much smoother bass line?

A BIAB user for more than 30 years (if you can believe it) !