Very good advice... I’ve used all kinds of containers for compots. I find that shallow works best. They do dry out faster but that’s what I want. Growth is directly related to how often you can water. This is not the same as how much water you medium will hold. As you know too much water in the medium will surely rot the roots off seedlings in a short time. I found some heavy duty seed starting trays at a greenhouse supply. They measure approximately 6” x4”x2.5”. They have plenty of drain holes (two levels). I put a piece of Egg Crate Light Diffuser in the bottom with a piece of plastic canvas on top of that. (Plastic canvas is used for crafts) This allows good air flow and prevents the bottom from staying wet while the top is dry. A compot set up like this has about 1 3/4” medium on top of the canvas. For me,in the house, I water every three days or so...