No there is nothing gained from adding short and long together.
20-30 MAP KPA would be funney since it mostly decel and low RPM range and sometimes fuel learn is off or on or just having switched from one to the other.
You'll gain nothing by doing all this since PCM is not perfect and many different driving conditions such as going down a hill from full to partly decel so numbers will never be perfect but again as long as trims rotate a bit lean and rich from zero assures O2s can also ramp up and down crossing 0.450 mVolts

If always a perfect zero then O2s would stay constant and that would confuse PCM.