Hanging out on the 2nd 4th 6th or even 7th in a melody creates tension as they long to resolve to nice 'safe' root, third or fifth chord tones. And as most songwriters automatically camp out on the root, 3rd & 5th any melody that avoids overusing them has an instant advantage in trying to be original.
Day Tripper, Get Back, Golden Slumbers, Help, I'm So Tired, There’s A Place, She Loves You, You Never Give Me Your Money
Ticket 14: Write An In-Key Melody Over Out-Of-Key Chords
Ticket 22: Bluesify Your Melody
Ticket 50: Stay Off The Root Note
See the full list of songwriting tips here - Tickets To Write