Since I brew 10 gallon batches very frequently, I should track separate 5 gallon batches more than I do. Instead, I rely on anecdotal memory and think I am comparing prior batches to current batches. But, since I brew similar (if not identical in all other respects), low ABV beers typically, I can give some "slightly meaningful" (meaning very non-scientific) data points on these things, such as when I forget to add the whirlfloc, or yeast nutrient, or I pitch a half cake or I pitch dry yeast.
New packets of dry yeast tend to give me the greatest lag time, but are usually more expressive than subsequent re-pitches of the dry yeast (now liquid, right?), especially with S-189 (because it is so neutral, perhaps?)
Forgetting the Whirlfloc means only a slightly longer time to clear and forgetting yeast nutrient doesn't seem to affect the beers, as long as I don't serially re-pitch without yeast nutrient (one year I tried without it and ultimately it just seemed to poop out after several generations of lager - a bit more lag and a bit less expressive).
But as Dave said, it is just my own "observation" and I may be tainted in some way to develop a confirmation bias...and no two batches that I make are precisely the same, since the malts I use occasionally differ, based on what my LHBS has available in sack form at the time of purchase. In the end, I just don't track every variable closely enough to make a scientific data point. So, I rely much more on those of you who are better at controlling variables to reach a more valuable data point. Cheers and thanks to the "sciency" types among us for all you do.