Question artists

[Amateur]

Question artists. What is the sequence of writing the portrait if the model is very little time for posing?

Imagine a time of war, specifically Italy, November 1943. The artist should paint a portrait of a famous military commander in the rank of Army General (later Field Marshal will be), in his submission there are more than 120000 people. No big battles, but the local fighting - across the front line, besides preparing for large-scale offensive, which should begin next week. Frontline situation does not allow him to pay for photo opportunities and a half hours, and then called into question. Apparently, the full-length portrait of one and a half hours in any form is not enough. You would start by writing a short sketch, the sketch and if you get a good sitters and approve this, they would do a portrait (starting, naturally, with those for the form and so on. You can write and then). Or would do a portrait at once without thumbnails, saving time? Finish the portrait would still have to then, no longer a model. The responsibility is large, this general is known, it knows everything. Any error will be noticed. What would you do?