As far as i know - shape fights are the only reliable way to get shards.
You can speed up this process a bit with debug mode (SHIFT+ENTER+F2), after it's activation you can click left/right CTRL and that will allow you to go any direction even if you encounter a fight, and you can do it until you encounter shapes fight.
By the end of such farm every section of location map can be filled with normal fights.)) Edit: Added a screenshot