How to figure injector dead time! Fake or Not

During my quest to find the injector dead times on the injector I'm certainly using I found the following post on a forum:

''Getting the injector dead time correct is important for getting a stable, accurate idle, and accurate AFR's while engine braking.Injector dead time will differ from the manufacturer spec if the "flyback" voltage your ECU applies to the injectors is different than that during the manufacturer's tests. Here is a method for measuring dead-time in-car.Procedure: Idle car while datalogging, and have a means of changing the injector electrical pulse width slowly up and down while logging. The car must have a reasonably stable idle at a fairly fixed RPM, and battery voltage must be constant throughout.Log MAP, AFR, Battery volts, and Injector electrical pulse width, while idling. Slowly raise and lower injector on time (I did it by changing the AEM's injector dead time vs. battery voltage, across 3 cells, straddling the battery voltage that I was seeing). Slowly raise and lower it until the RPM starts to drop significantly or the car starts to misfire. I could go from 11:1 to 16.3:1 or so and back. Do this several times, it may take you a few minutes.Then examine the datalogs. Do an XY plot. Plot MAP divider AFR on the X-axis, then injector on-time on the Y-axis. You can use AEMLog for this, or MS Excel. Excel has the advantage of having a linear curve fit ("trendline, linear"). The data points should form a line. If you project this line to the Y-axis, the intercept is the dead time. See attached. In Excel, do a scatter plot, then add a trendline. Select "linear", and in the options, select "show equation". If your data is clean and has little noise, the Y-intercept will show in the equation. If not, select "Set Intercept", and try different values until the trendline appears to describe the quiet part of the data. In my example, it's 930 us. This is for a friend's 750cc RC hi-impedance injectors. Note that on the bottom left of the data, there appears to be an arrowhead shape. This is noise in the data, due to a lean misfire, at narrow injector duty cycles/leanness.''

Can this be accurate? or at least close to the makers spec? I hope those with more experience in tuning would give us some insight into the matter. I think a tool like this might be helpful if you tuning a car with injectors that are very difficult to find any data on like mine. Personally, I haven't tested it yet

It is possible to do something like this. Modifying cell at a moderate load cruise may also work, potentially better depending on idle quality, if the motor has agressive cams/port it may miss too much or hunt too much to make any significant muxture changes at idle give consistent data.

But with this method, we can get data only for a certain voltage area so this means that we have only one value. For lower/higher voltage rates?