I don't think it is explicitly meant to include any bonus. It's just an estimator. Here are some actual pitches per inning allotments, based on calculating total pitches using actual SIM fatigue levels, so they are reasonably accurate subject to some small rounding errors. 15 pitches/IP is fine as a quick estimator, but understand that it may take some in-season pitch count adjustments to keep some guys on track.
'08 Joss - 13.9
'08 Brown - 14.2
'10 Walsh - 14.6
'95 Maddux - 14.9
'00 Pedro - 16
'18 Sale - 16.9
I'd move down a bit from 15 for low-K/BB pitchers and up for high-K/BB pitchers.