Sort of...At least with boil IBUs there are established mathematical formulae that the recipe editor uses. When you change the length of the boil time, the IBUs change in the recipe. When you change the whirlpool time or temperature (definitely both are strong factors in actual alpha acid uptake) the IBUs stay exactly the same. Only when you change the percentage is the IBU count changed. The 10 percent default is pretty much a WAG...that's not the case with the calculator for the boil function.
Well, it's not a complete WAG...................
It's a studied WAG. Understanding the utilization of lower-than-boiling temperature hop additions is a brand new area of brewing, and at first experienced brewers and those who wrote brewing texts strongly stated that 0 isomerization happened at temperatures lower than at boiling. But we all know that isn't true. Trying to determine a formula that takes into account things like wort gravity, temperature, time, etc isn't that easy when there are that many variables, and some research still needs to be done to even come up with a formula for this.
The best we could do was add the whirlpool/hopback hop additions to the software, give a default utilization percent that start with the boiling temperature, and allow the brewer to make the decision based on his results, his palate, and (hopefully) some lab testing on his own.
I chill faster than some, but not as fast as others, so even if we had a perfect formula at the outset, the results would still vary greatly among brewers.
By allowing each brewer to either go with the default or choose their own number based on their research and results, we can still have the whirlpool hops "count" toward the IBUs if desired.
In my Beersmith 2 software, all late hops added at flameout or whirlpool always had a 0, and I knew that wasn't so for my big IPAs. This software allows me to make the decision on what to do with those numbers and I like that.