Some small places I know will repitch until they see a need for a new order from the yeast supplier. This is done mainly by taste.
One speaker at the NHC said they go 5 repitches before reordering.
Some big breweries have yeast propagators, so they can grow up large pitches in house from their yeast bank. These breweries have labs with trained personnel to take care of the yeast.
A few of the Alan Pugsley-built breweries have repitched the same Ringwood culture since they opened. I am fairly certain that Shipyard and Magic Hat are members of this group. One of the beauties of Ringwood is that it is true top-cropper. All of the Pugsley-built breweries top crop from open fermentation vessels. Top cropping is the only way to go if one wants to repitch a culture indefinitely (Harveys also top crops).
Arcadia is supposed to be one as well.
Yes Arcadia uses Ringwood. One of the Brewers said it was a "Fussy b****" in that it would require more attention some times, ie rousing.
Grizzly Peak in Ann Arbor had a Pugsley system and would struggle with Diacetyl. They changed to Essex and the beers are much improved. They open ferment and top crop. The problem is they don't have the tank time for a long D rest, they were doing close to 1600 barrels on a 7 barrel system. WLP -022 produces clean beer for them.