Time employed for writing I am looking for any indication of how long should it take to write, let's say, a paragraph, for a non-native English speaker (with a good knowledge of English). I know that for the writing process of a paper or essay one should take in account also the time required for research and mind-mapping, which is not easily quantifiable. I am interested in some reference for the time needed to translate the mind map to a paragraph. The only time indication I found was in  http://www.scripps.edu/milligan/em-journal/pdf/Scientific_Writing.pdf (e.g Introduction: 3 days) , but the author clarifies that it is a personal opinion, and anyway it includes the mindmapping procedure. I can spend half an hour writing and editing a couple of sentences (already knowing which concept I need to express), how can I know if this time it's abnormous? 

(meta: Feel free to move to personalproductivity if it's the case, I was unsure but then I thought of posting in academia because I am specifically talking about scientific writing)
As a teacher who has taught many non-native speakers subjects in English, I am quite confident when I say that the time will vary by the person. Some people are quite strong and write faster (and better) than some native speakers but others write very, very slowly.

To have anything meaningful, there must be some quantifiable tie back to English level (what does 'good knowledge of English' mean to you? IELTS 8?)

It seems you are interesting to know if you are performing well enough compared to some standard, but we would first need the standard (and it does look like you're trying to find the standard) and that standard must take into account more than just the information you've provided (how much experience do you have writing in general? how good is your English? what kind of writing are you doing?).