Solo training allows you to focus on yourself and builds your mental toughness. You have your objective and it is solely up to you to complete. It comes down to you, your bike and the ride. With no other cyclist to use for motivation and chase down or ride away from, you find your own personal motivations. Done successfully, you will not only make yourself physically stronger, but now you are mentally stronger.
Your plan is unique to you. Whether you are working directly with a coach, using a training plan, or have set out your own plan, that plan is designed to get you where you need to be. It is based on your time constraints, strengths, weaknesses and goals.
Focusing on your individual plan provides several key benefits. First, even if your teammate or riding partner is on the same schedule for the day, most likely your target numbers for efforts, or even your recovery between them, are different. You do what you are supposed to do and they do what they are supposed to do, it’s that simple. Next, we all have a competitive side. Training with others can tempt you to compete against each other, forcing you to go above and beyond what you are supposed to be doing. It can also have the opposite effect if you have to tone down your workout for your partner. Riding solo keeps you in check and allows you to focus on your form too. You are able to pay more attention to your position on the bike, pedaling technique, etc.
Riding on the road has enough natural distractions. Your buddy riding next to you chattering away can take your mind out of the game. The less you have pulling you away from your objective, the more you can concentrate at the job at hand.
From a purely selfish standpoint, a big benefit to riding solo is that you only have to answer to yourself. There is no meeting time, other schedules to accommodate or having to wait for those that are late. You are not dependent on those around you to dictate the pace or effort. You get to choose the route. If you feel good you can extend it, or if the legs are shutting down you can simply soft pedal back home.
Whether you have structured your own plan or you are working with a coach, your schedule was written with specific goals or targets in mind. Each day is a separate puzzle piece that when put together will hopefully help you achieve your target. Training by yourself allows you to follow your prescribed workout by concentrating on your plan without distractions