although it's a bit random there's actually a couple things locked behind taking a walk. maid job being one of them.
As I said it's random. Although I haven't managed to trigger anything with the walk into the deep forest yet the other walk has a very low random chance to unlock a couple different things. One of them being unlocking the maid job. Due to randomness don't be surprised if even a few or even more walks in the city fail to unlock anything. I had to do quite a number of walks even after I maxed sizes before the maid job finally unlocked for me.