I kinda did this strategy with Pet Hotel - Adding anyone and everyone I came across until I had a gazillion neighbors. It worked well in the beginning for leveling, making money, receiving gold, etc. but as I had less and less time to play (ie, I hit '30' so I didn't care about xp anymore) and pretty much everyone had settled into gold buddies, having that many neighbors was more of a burden than a good thing. I don't like having so many neighbors that I don't recognize their names as being my neighbors. I tried to fix it in Pet Hotel by removing all my non-tipping neighbors (zero & 1 star) but it was too late so I ended up quitting that game.
So in Dragon Story I'm trying a different strategy. I still have what I consider 'way too many' neighbors, but it's no where near a gazillion, lol. I'm able to visit them all most days and leave fun messages on their walls when I do. I'm resisting the 'gold buddy' system by including everyone who visits me, gifts me (that day or any preceding one still showing up in my 'gift back' list, or just asks for a map (since that tells me they're actively playing) in my random gold gift list.