Working just for Home Page:
Directing all your links to home page is a bad practice. Most of us build link just for home page. If you see your linking data on webmaster tool you will be surprised to see that 90% of your links are pointed to home page. If the link profile is small then nothing to worry. But if you find you have 3000 links and 2900 is targeted just to your home page then it looks unnatural and who knows, you can be caught by their spam filter either by algorithmic way or by manual action.
Lack of Keyword Diversity:
Choosing just one or two keywords for your landing page backlinks is another bad practice. Targeting a single keyword and building all the links for this keyword indicates your site is over optimized. It could be another threat for your campaign.
What do you think about these two points? I'll love to hear your opinion.