Is getting x4 of every card in one set a good strat for getting rare wildcards?

So iirc, once you have 4 of a card, getting a 5th from a pack auto turns it into a wild card. As a newbie, is it a valid strat to work on unlocking every card in the smallest available set, then buying something silly like 90 packs in said set. This therefore guarantees me at least 90 rare wildcards, right?

Or are there better ways for a ftp player to acquire rare wildcards?