I have never tuned an EFI car, and am only familiar with carbs,
And there are several FABO members that considerably wiser than me on these matters.
But
I offer you this:
I cheat.
I have a stick-onto-the-window, accelerometer, that has data-logging capabilities. Mine is a G-tech-Pro-SS. With it, you can do a test run at any load setting and over what ever rpm range you want. It plots acceleration over time. Then I go home and play it back, looking for anomalys.
I also have a dash-mounted, dial-back, timing box with a range of 15 degrees; so I can change the timing on the fly, from the driver's seat.
It shows up on the SS as faster or slower acceleration thru the speed or rpm window.
The two tools cost me less than $500, and have paid for themselves many
times over.
Oh yeah, I had to make a throttle-stop early on, for Part-Throttle runs, for repeatability.