This is one of my recently done hedcut for one web project. The number of stipple portraits drawn for this client is already over than 30 and I was very happy to work with them.
When you draw for the same client for years the most difficult thing is to keep the style which you have been using all that time for his portraits. Dot size and detailization level should still be almost the same. You draw portraits for another client with differents requirements and it may cause the changes in draw technique. What you have to do here is to keep an eye on previous hedcuts from this series while drawing the next one.
Finally you learn to switch easily but this is the dead end track. What you really need