I used to drain pretty much right away. The only reason it takes me slightly longer to drain now is that I wait until my sample cools and I get a good pH reading. Although my sparge pH reading is pretty much a formality now because I'm adding 1.5 to 2.0ml of acid to the sparge water as it's heating so the reading is just to find out where it is, not to see if it's too high. I agree that a higher-than-desired kettle pH can futz with your beer as well but let's put it this way: If I had a mash pH of 5.2 and my sparge pH somehow got to 6.2, my kettle pH should be somewhere around 5.7 (I realize it could swing a little) which should not cause a problem in the kettle. That would suggest that in that example, the 6.2 pH of the sparge caused more damage to the beer than the kettle pH. I have actually been thinking that I'm overdoing the pH lately because I have had some batches with a mash pH of 5.2 and some with a sparge pH of 5.2 or 5.3, leaving me with a kettle pH of 5.2 to 5.3 which is probably too low. I may be making more of that than necessary but I plan to ease off the acid a little.
That is an impressive pH you obtained in your sparge. I'm glad you finally found the answer in acidifying your sparge water!
