I was trying to think of an example of how certain chasing can be undesirable. I got one example.
Let’s see you have very high alkalinity, for whatever reason, and you want to lower it.
Here’s a bad way to chase numbers: dump a bunch of unmeasured acid (muriatic acid) directly into the tank. The pH will become VERY low, and might kill many things in the tank.
Here’s a good way alternative: stop dosing alkalinity, and let it come down by itself. If the alk is very high, and you want to be a little quicker, you can add acid to new make-up water. Let it aerate heavily for 1 day to back up the pH, and then do a water change.
Both scenarios wanted to chase a lower alkalinity for their tank, but one was much more harmful than the other.