The thing about the x amount of times medals are they're lifetime things
"Oh wow, I've rode the bike how many times?"
"I nicknamed 10 Pokemon?"
"Can't believe I streetpassed 1000 people!"
"Wow I do <x> thing a lot"
Stuff you just gather by playing the game, not something you actively go after.
So something like the Dowsing Machine medal was pretty neat. "Wow I found 150 of these things already"