I can still get two packs of 05 for the less of a price as a single liquid 1056/001. Two packs of US05 should be enough to ferment almost the biggest of the big.
Nevertheless, I do use Mr Malty app to know how much I need to pitch. If it is just a slight over/under pitch, I don't worry about opening another pack. Some days I will plan to brew two, and if I am using US05 (or notty/any other dry yeast) for both, I will actually divide up over the two packets to the real numbers to be close to where they should be.
But, I make a starter for EVERY beer I brew from liquid yeast (except sours). I do it just to make sure it is viable.