Not sure I understand what you are trying to say, do you find the prediction to be helpful? 150-190 BPM is such a huge range, what useful information can be derived from it?
I've done a good session if I push to 155 bpm. I don't need to worry about finger-sticks for lactate accuracy, because there's no-risk I'll do twice-a-day twice-a-week threshold sessions.
If I'm not even in the low-end of that huge bpm range, I quit and take a recovery day.