IMO, no. Different people might tell you otherwise, but why do the minimum? 😕 It costs $4 for a pack of 6 cards and 44 cents for a stamp! You want to set yourself apart from the other applicants, good manners is an extremely easy way to do that.
Little things matter. You don't know who is old school (like me) where a written note will go a long way. Err on the side of being polite.