I'm using the an SEO extension that allows me to add a canonical meta tag to layered navigation pages.
Next to this option, the extension states:
Don't use the "Current Category" value if the "Allow All Products per Page" setting (System -> Configuration -> Catalog -> Frontend) is disabled.
In other words, enable the "view all" option in the catalog before using the option to add a canonical url to the layered navigation pages.
What this does then is make the canonical look like this:
<link rel="canonical" href="https://www.example.com/category?limit=all"/>
Is this a good thing to do?