I few years ago I was prone to pick a new linguistic challenge to practice and perfect each year. One year it was the difference between "who" and "whom" (if you can answer "hiM" to the question, "whoM" is appropriate,) the next year it was the difference between "affect" and "effect" ("effect" is a noun, "affect" is a verb except when talking about a person's demeanor, then it is a noun".) And then one year it was replacing "but" with "and" when appropriate. That one, by far has been the most impactful on nearly every facet of my life, especially when it comes to more effective communication.
The basic premise of why this switch can have profound impacts is "but" is a separating word, "and" is a joining word. The implicit connotation of "but" can create a "true/false" or "false/true" paradigm for the listener. For example "You are doing a great job BUT, those reports could be more concise." In this example, the listener pays more attention to one part more than another, which can be confusing and have very mixed results. The listener can come away thinking the feedback on the reports is not that crucial since they are doing a good job, or they can come away thinking they are not doing a good job at all. Regardless, the listener can choose which side of the sentence is more true and which is more false.
In contrast: "You are doing a good job AND those reports could be more concise." It is subtle and it can be easier for the listener to hear both sides. At the very least, especially when you are providing feedback, it can make people be more receptive. Which, if it only impacts that area and you find feedback easier to give as a result (and they find it easier to hear) that could be huge! Also, "but" can put a negative spin on the sentence since it is effectively a negating word.
That's not to say "but" isn't appropriate in some contexts. My practice included re-reading emails and articles to find "but" and switch it to "and" to see if it made as much sense or made my sentence more powerful. 80% of the time, it was better. Occasionally I would emphasize the AND to ensure people knew I meant both sides of the sentence.
So the simple guidance is, if you mean both sides of the sentence, use "and." Practice it in your writing and be aware of it in your speech. It's a small shift AND it can make a huge difference.