That is what it is all about for me!
Here's how I arrived at those as pars/standards/goals for myself:
Identify the performance level for top-of-the-heap, champion, properly equipped, competitive shooters. Then work to duplicate or improve upon their performance using my own chosen gear. It's that simple.
A sub-2 second Bill Drill is a longstanding benchmark for Master class USPSA shooters using race gear. A lot of people do a little better than that, but sub-2 is a pretty decent standard at least, especially if you reduce the target size down from the full lower A-zone. So I ran with that.
About 1.5 seconds is the time Ben Stoeger, Robert Vogel, and Dave Sevigny are documented to have done on the first three strings of the IDPA Classifier (two body, one head at 7 yards), at least in one recorded instance for each of them So my goal is ~1.5 on-demand, and better than that in practice and as I improve over time.
Four body and two head - that's not a widely practiced drill, but it's six shots, so that's where I want to say screw the math, I want 2 seconds or less, just like the six shot Bill Drill. Realistically, it is harder than a Bill Drill and that's where I begrudgingly accept a bit over 2 seconds. But it's similar to the historical USPSA Master class standard for a Bill Drill at least.
Two head/CNS shots - with the FAST such a heavily practiced thing here at PF, a sense of times can easily be had on this. Using a 3x5 card as an example, Dave Sevigny shot the pair in 1.62 seconds on his world record runs on the FAST. So about 1.6 seconds is good. AIWB may be faster than a strong side draw, so really I'm looking for less than that. I have done it enough to know that when I do it well, the time is more like ~1.3x for the pair. So that becomes the goal time to attack for on-demand performance.
Identifying top-level performance and then trying to match it using tougher gear is a great way to improve. Doesn't mean that performance will be factually realized, but used as a goal it is highly productive in realizing improvement, sometimes huge improvement.