At the end of the 2.30hr session

I'm not doing anymore to it.It has a rawness I like.If it was a commission I'd tone down a few marks and make it more flattering.You never get a flattering portrait from a model as its really hard to sit totally still for 20mins at a time.We have a break every 20mins for a few minutes and then they go back into the pose..By the end of it they all look haggard and we can only paint what is there! You can't get them to smile and stick a grin on them as when you smile the whole face shape changes so if you just stick a grin on it won't look natural + you won't get a likeness! Believe me I tried it once with a public 20min sketch & it didn't work!The first time I didnt get a decent likeness so I learnt quickly.
As a compronmise you can get a nice smiling photo and then once you have the face shape use a model for the colour etc..