Yes and no. The hydration of your sourdough starter matters not so much for the health of the starter itself. But it will matter for the recipes you'll make with it. In other words, if you accidentally add more or less water to your starter, don't worry, it won't go belly up on you. Just continue feeding it in the right proportions in future and it should be fine. But how much water is in your starter will matter when you add the starter to the recipe. That's because every recipe will have instructions for starter hydrated to a specific level. For example, I use a 1 cup flour to ¾ cup water ratio in my starter. Some other recipes use more water, some less. So all the recipes I post are tailored to the hydration specific to my sourdough starter. If your sourdough starter recipe came from somewhere else, and you are planning to bake a bread from my blog, you'll need to adjust the level of liquid in your bread recipe up or down based on how much water is in your starter.