I try to send them lots to get pics but it never works, and I end up giving up lol. Not to mention it takes me forever to type on that little keyboard so I couldn't be bothered to sit there and type out a letter to every villager every single day lol
Exchanging letters with villagers can be quite entertaining, I would probably do it more often if it weren't so time consuming to think of something and put it to paper. The only time when I don't put effort into my letters is when my wardrobe is about to burst.
I don't do it daily, but I do send my villagers letters often... Especially if they're wearing something I don't like, I've been known to send them 10 new shirts at once to get them to change it. XD
I write letters every day but only to my two favourite villagers Simply because I'm trying to re-decorate the inside of their houses and attaching presents to their letters seems like the easiest way to do it!
I may do it maybe a couple times a month. I would do it more often, but I just feel it's kind of tedious. I want villager pictures, yes. But doing favors seems like it'll work just as well eventually.