Yes. Writing paragraphs is an organizational strategy for your reader so that your ideas are made clear and easy to follow. To do that, you need to focus on one topic or idea per paragraph. You unify your paragraph by using specific examples that support the topic sentence. The usual requirement is 2-3 examples, but you don't have to limit the number. To make your essay cohesive, you need to discuss and analyze how or why the specific examples you included support the topic sentence. And finally, you need to wrap up your paragraph with a concluding sentence (synthesis) that reaffirms and restates the main idea of the paragraph. If you stick with this structure--Topic sentence, Example/Evidence, Analysis, Synthesis--you will write a clear, focused, and unified paragraph.