software are not preferred and it is best practice to do manually. this is because all the software are not 100% perfect.
Chances of you being accepted for a free one way in under a month is slim to none anyways. so guess software could be seen as naqtural progression through that avenue.
Don't create problem for yourself by using software for link building after penguin update go for manual link building.
some white hatters wouuld agree building links manually would be they way to go, some grey hatters would use a combination of manual linking and software for automation, blackhatters use software such as senuke,scrapebox,xrumer and such to build backlinks. from personal experience I prefer the greyhat method if you're going to build links using software dont overdo it or google will eat you alive and sandbox your site
The best way to build links is to do it manually! Use automated link software if you want to get banned from Google!
What could be the reason not to use automated tools? If you are stupid and blast out 1000x the same bookmark or article withing 30 mins, of course you get punished or ignored by Google. But if you use it wisely (good spintax, scheduler over a long time), I dont see any problems. This is what you are doing manually as well. How should Google decide if a bookmark was submitted automated or not? Web 2.0 sites like Squidoo or tumblr I do manually. But the reason is that the pages are too complex for a program.
For me, it's xrumer.... I know that's like a dirty word in some circles, but it works well for what I do. Sorry natural link builders. I'm not trying to pick a fight, just giving my opinion... (Please don't kill me)
If you've never use automated back link software, better don't start! It will only get you in trouble with Google these days. Have you heard of Google Penguin update? Links form bad websites can hurt your rankings, in stead of improving them.