You'll manage to get quite a few from this and if your site has something really interesting it'll take off. However most stuff that generate their own diggs are something ground breaking which for most sites aren't.
so I tried to find other ways of which I could get my sites and other sites digg. I manage to find a way to get people to willingly help me digg my sites. I wanted it still to be someone original so I asked them only to do it if they genuinely like the site.
I used to offer social bookmarking services and it went successfully I was able to get people to do what I want them to do and to digg the sites that I needed dugg. However please understand that digg has a big protection against spam so that isn't a very good alternative.
Also there are different factors to getting on the front page I was able to get a good amount of diggs more than most but it didn't hit front page since it's really competitive.