Yes but rememeber that is only a guide...
Here goes a little diatribe, bear with me:
Most calculations are done at at 100% injector duty cycle. I know what you're thinking, but that's not a problem for a street engine or a drag race engine. If you are stuck only wanting 80% duty cycle then most everyone needs bigger injectors or they are on the edge. There are a bunch of fairly stock GT's making around 260 at the wheels with 19# injectors. Do the math with .5 BSFC, that's only enough for 304 crank HP, if you then take 80% of that, they are only good for like 240 at the CRANK.
Should all these guys switch injectors? Let's take a stock GT with 260 crank HP, that's even under the 80% of the 304 number. Does that mean that Ford doesn't know what they are doing and the injectors are too small? No. A Cobra with 8 24's, 8 times 24 divided .5 is 384 FWHP, 80% of this is 307 FWHP, again, Ford is violating "the 80% duty cycle rule." There are also a lot '01 Cobra's with stock injectors, making over 300 RWHP. Are all these on the edge and in danger of blowing up? No.
One final example: lets use a '03 Cobra. Eight times 39.6 divided by .6 (and if you see the a/f ratio on stock cobra's, it's way greater than this) is 528 FWHP. 80% of this is 422 FWHP. How many '03 Cobras are more than this at the wheels, are they on the edge?
The thought of only 80% injector duty cycle came from people thinking the injector needs enough time to cool off. And this is true, but to overheat an injector it takes 60-90 seconds minimum at 100%, how fast do you think you'll be going in 90 seconds? And it's almost impossible to be at 100% duty cycle for extended time. It's a calculated game that almost everyone plays, including the OEM's. Now, in a road race motor, this is very, very true about giving it enough time to cool off and then maybe you want to size for 80% so it does have that cool off time.
It is virtually impossible for an injector get unstable over 80% duty cycle unless it's there for an extended period of time. I knwo most will disagree, but they have no data to the contrary. Clearly the OEM's run their injectors way past 80% and there are very, very few injector failures.
Now if you ran a car at WOT ALL the time when you are "on the egde" it may go lean..." but again, howmuc time CAN you spend at WOT?