(Unless you're Ken Nagle, in which case you do it right to left.) However, there's an important distinction to make here: you need to see what you're actually going to want to cast at each mana cost, not what you can cast at each mana cost
Even without intending to, you'll quickly work out which cards aren't pulling their weight, and start seeking replacements
For what its worth, you could also get the opposite scenario, though it is significantly less likely to find a stacked booster box than a dead one
5 Runaway Steam-Kin Can Generate Three Mana For Every Three Spells Mana-generating creatures are always pretty useful, and Runaway Steam-Kin is an absolute powerhouse in red decks with plenty of cheap spells
Aether Theorist, for the price of two mana, is far more powerful
Thats the kind of question great game design always asks, which leads us to unearth the unearth mechanic