There are lots of reasons and strategies for using toned grounds here are a few that I use.
When painting outdoors I will carry a few differently toned panels.
A Blue gray panels is useful on a sunny day as the blue will match the sky and I can paint dark trees over the dry ground, add any clouds and we are well under way in a short time.
A warm pink grey is good under a predominantly green landscape as the warm colour showing through the green give some life and vibrancy to the view.
Mostly I will not pre-tone but quickly paint in an overall tonal wash that will become the background and half tones, while the wash is still wet I’ll wipe out the lights to get the placement. Then I will go in with the shadows, then the lights. This is a quick way to paint as you establish all the essentials in the beginning.
“What peaches and what penumbras! Whole families shopping at night! Aisles full of husbands! Wives in the avocados, babies in the tomatoes!—and you, Garcia Lorca, what were you doing down by the watermelons?”
— Allen Ginsberg
Are you ready for a Journey
PS Critiques always welcome but no plaudits or emoting please.