This question has been thrown at SEO’s as long as the practice of link building has been alive, and is one that the team at TBS Marketing often encounter from new prospective clients.
As with all SEO practices and techniques which influence Google’s Rankings, there is, of course, no exacting and definitive answer to this question. There are just so many variables between different links which will influence their power and speed to affect rankings – either negatively or positively – and there are many other factors outside the link itself which one needs to consider before realising how impactful said link may be; such as the competitiveness of the keyword being targeted, rankings currently occupied by the website being linked to, its relevance for the keyword and many others.
Even if we could give a clear and definitive answer, it would likely not be definitive for very long due to the very fluid and evolving nature of Google’s algorithm and how closely guarded they keep it.
If you still want as close an answer as you can possibly get to this question (over-looking what I have mentioned above) then Kristina Kledzik (a regular contributor to MOZ’s blog and a respected SEO expert) does a better job than most in her attempt to best answer it. Her findings, following a practical investigation she carried out, together with her knowledge, can be found on an interesting article she published herself on the subject here.
Although Kristina does her best to give indications on time taken and level of results to expect…that is still what they are…an indication. One of the key points to take from her investigation and report is that building links DOES WORK but, as with many things that achieve results, it takes time and you have to be patient. Ultimately this is the message our SEO specialists at TBS marketing convey to new prospects when put on the spot with this question. This is not to dodge away from giving a straight answer; on the contrary it is a very straight and honest answer. It is vitally important that we always set our clients expectations right and do not over-embellish or exaggerate time-lines of when they will see results from our link-building; or any other strategies for that matter. Some campaigns see much faster results than others and “fly out of the blocks”. Some take a little longer. Ultimately we get to the same end point and are confident in achieving results for all clientele we take on-board and giving them a return on their investment. However, to achieve the goal a degree of patience must be observed. After all, patience is a virtue!