Did you find that buying adspace to promote a blog was more effective long-term than just directing people to the product/company landing page? If it is a company blog.
I've found that adspace can be effective in a number of occassions. Firstly, if you create a great asset on your blog, for example, if you owned a travel blog and had created a downloadable travel guide for backpackers to save money, then creating a banner that went directly to this asset would be really effective toward increasing the number of downloads. On the other-hand, if you're looking for traffic that is going to a general landing page then it may be best to point the banners to that instead of adding an extra layer to the users journey through the website.
In short, if you're looking to actually get people onto your product pages then get the banners to point to there. I have a number of clients, primarily within the AV industry, that do this as part of a long-term strategy and it works well. On the other hand, I use this on my personal blogs in the short-term to promote specific assets in order to increase my readership. Unfortunately there isn't a 'one-fits-all' answer to that question but I hope this has helped.
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