What about sub 5 gallon batches? Using WLP001 on a 3 gallon pale ale. Starter?
Risky. 3 gallons is not far from 5 gallon, and with liquid yeast you never know for sure how good the storage was between manufacturer and your own refrigerator. I'd make a starter for 3 gallons, even if only one liter. Only exception might be for hefeweizen where underpitching is arguably better than the standard pitch rate anyway.