I’ve mostly painted on watercolour paper, and just last year bought some w/c pads. I re-use my blah-paintings paper by first painting on the back, or trimming decent areas to put on cards. Then, I may re-purpose some by using the gelli plate to paint on them with acrylics, using those for cards or in mixed media. Recently I’ve been dipping yuck paintings in acrylic paints to create neat backgrounds. I’ve also gessoed one side of my paint fails (usually on 300 lb paper) and used them for acrylic pours.