B23 adds variety to blockstrings which keeps your opponent on their toes. It's always good to mix-up pressure visually so that if you decide to add sneaky things in between, or throw, your opponent is less likely to see it coming.
For example:
F2 xx Breath
B23 xx Breath
B2 xx Heat Zap
B2 xx Breath, walk forward slightly, 3 xx Breath, F23 xx Breath
Once your opponent expects you to attack over and over again you can take a few risks:
F23 xx Breath, F2D1
F23 xx Breath, DF+3
B23 xx Breath, airdash cross-up
B2 xx Heat Zap, slight pause, F2~Trait, F23 xx Breath or dash in throw
B23 xx Breath, walk forward slightly, [MB] F3, (if blocked) continue pressure