Clean Up Your Update Loop - Unity C# Development Tips
Multiple return statements instead of if statements can end up causing more headaches than they fix; as can the opposite. It's a tool to be aware of, but it's also developer preference. Just do what you find easy to read and are comfortable with.
In JetBrains Rider, you can right click on an if statement to pull up "Context Actions", and have it "invert if" for you - and you can do it again if you change your mind. You can also select a block of code in your Update loop and right click, then go "Refactor, Extract Method" to automatically pull a function out. Neat!
Also, I know you can write the return code in one line: "if(!a) return;" without the curly braces. I don't teach one-liners to my students as it's a common cause of bugs specifically when transitioning from python to C#, as they look similar but behave differently, so I keep curly braces explicit to avoid confusion there.