There is never a day when practice in your journal won't be beneficial to you. No matter what medium or papers you choose. No matter than rain forces you to journal inside. In my classes I encourage botanicals and still lifes as a way of sharpening your sense of awareness and perception. The examples here are a way of looking at one subject with a variety of different tools. While watercolor is my chosen medium, I do feel that it gives one a wonderful sense of working with "value" when you work in one tone.
The tools used here are ebony sketching pencil, water based ink (I used a black Tombow pen), watercolor (Winsor-Newton), water-soluble graphite (made by General), watercolor pencil (Derwent), and watercolor with ink (here I used permanent ink a .005 Micron which is my old standby). Except for the Ebony sketching pencil one, I used water and a brush in doing all the others. All of these would look different if I chose a different grade or finish of paper. I'll talk about journals themselves and paper another time.