No, not recommended. Some SEO agencies in HK may accept but we would like to state that it is difficult and ineffective for an SEO campaign with only one keyword.
For example, “SEO” is one of the most difficult keywords to push, you need other long tails keywords such as “SEO Hong Kong”, “SEO HK”, “SEO Expert”, “Google SEO” to support. Although those keywords have less search volume than “SEO”, they are more easily to get to the first page, and hence you get traffic in a short period of time.
And if users are looking look for services or company, they would search “SEO Agency”, “SEO Company Hong Kong”, “SEO Services”. If you just optimize one keyword, you would probably lose a huge portion of potential clients.
Moreover, over-optimizing one keyword may easily get penalized by Google.