I think this is really up to the individual!
We have a Yorkie Poo who only goes outside, she's 17 lbs!
Wrigley goes on a pad in a litter box almost all the time, but she will go outside when we are in the yard and she's never been confused about it or have any accidents!
Our new little girl will go on a pad first thing in the morning when she gets up and then not again at all, though she's finding the tile and carpet to her liking at the moment.
She's great about outside!
We love the idea of the pads/litterbox, especially in the winter or rainy weather, but everyone is so different!