I’ve often considered the “to crash or not to crash” debate with respect to yeast starters. Having made many, many starters on a stirplate, I’ve always pitched the entire starter (on average, these are 1.5-2.0L starters) as close to high krausen as possible. Depending on the age and viability of the yeast used, that can occur in as little as 8-10 hours or, in some cases, as long as 3-4 days. In general, my approach is in line with Jamil’s Mr. Malty article on yeast starters:
“…the bulk of the yeast growth is done by 12-18 hours. I like to pitch starters while they’re still very active and as soon as the bulk of reproduction is finished, usually within 8 to 18 hours. This is really convenient, because I can make a starter the morning of the brew day or the night before the brew day and it is ready to go by the time the batch of wort is ready. There is no need to make a starter a week in advance, because I pitch the whole starter, liquid and all (up to a certain size of starter). Yes, you can wait longer and completely ferment it out so you don’t have to pitch the liquid, but if you’re going to do that, you should use a larger starter and allow the fermentation to go complete cycle over several days, chill, decant the beer and pitch just the yeast. If you’re making a smaller starter, it is better to just pitch the entire active starter within about 6 to 12 hours of pitching the yeast into the starter.”
So, an answer to the original question is it all depends on, variously: the size of the starter, the viability of the yeast, your own personal schedule, etc…
For those that crash and decant, do you let your starter completely ferment out and then crash? What’s been your experience (plus/minus) with differences between pitching a decanted starter vs. pitching the entire starter? I would like to be able to pitch a volume less than the entire starter (never need an extra 2L in the fermenter), but I’ve never had any issues with doing so (nothing deleterious to overall flavour, etc.).