Thanks for the questions!
I DO use zigzag but rarely for the evergreens. I find it needs to be adjusted too often. Most of it is just twitch muscles moving the material in the direction I want. I can set the speed of my machine and forget it. Unlike a lot of instructions for free motion work I seldom use my whole arm. I rest my wrists and use my fingers to move the fabric. Yea you need to readjust often but I find it less tiring. The zigzag stitching was used as a final anchor on the really exposed edges like along the path and anywhere the colour difference is so great loose edges show up to much. I strangely I use a slight zigzag when I do the smooth edged deciduous leaves. It makes them less regular and to me more realistic.
Have fun. There are several non woven materials that you can use as well. Just a word of caution. STEAM your canvas well and shrink it. This will tighten it. And every once in a while re-steam what you've done and stretch out the gathers.
MK

Fabulous piece! I just finished taking another class on these techniques and love doing them. Yes, mentally exhausting, but it does seem to come a bit easier as time goes on.

So beautiful it takes my breathe away!

This is so beautiful and inspiring, and I can't even begin to imagine how you do it.