One of the important parts of a tempo run is your ability to feel the pace. This is one of the main reasons it’s good for your training to do these runs outside. Your ability to learn what the pace feels like will help you a lot when it comes to race day. It also enables you to look less at your watch and focus on running off of feel and effort. Looking at your watch is important to make sure you’re staying on pace but you should learn to feel it.