Last month i work on a SEO project and I did on page optimization . I try to stuff those keywords in content which were not making sense. The site was related to a doctor . To get ranking on high searches keywords i use doctors rather then doctor then after some time i check there was not ranking in google for keyword " doctors" . I assume i should use keywords related to content i just replace "doctors" to doctor . Now I having ranking in google i assume google like human . Do other SEO guys have same experience like this ?
When you do the change from "doctors" to "doctor", I think, your site will have another competitors on ranking. It looks like as the case of doing SEO for "people" then change it to "person". I'm not sure but your info can be helpful.
First of all google do not consider on keywords tag. And second and important knowledge is Google select always keywords from your body keywords according to your on page optimization like heading tags management ..... flow of keywords etc. So its completely your imagination only coz google decided already for your keywords after crawl your contents ...... does not matter you are putting Doctor or doctors in keywords tag.