Practicing with someone is surely one way to get better faster. Companionship is one aspect that you miss out on if you never practice with a buddy. Having someone else there who’s encouraging and fun to be around is almost always a good thing.
A buddy can help get the practice session going and keep it organized. A thoughtful buddy can help put a contest in place so that competition can be had. He can help you know when to continue and when you are done.
Folks just don’t practice enough in the first place. Nor do players take advantage of practicing with a buddy. It’s even better if your practice partner is better than you. This causes you to have to pay attention. It can pressure pack the practice because you don’t want to lose. It can help you stay with the practice session a little longer because it’s fun and no one wants to leave. All factors that will contribute to you spending productive time working on your game.