Disagree. Sure, I flew the vast majority of my time with my instructor but the couple times I flew with a safety pilot it allowed me to start to mature my thought processes that I was learning with the instructor. By the time I flew with a safety pilot I KNEW what I was supposed to do so and to not have constant feedback from the right seat allowed me to flex my mental and motor control on my own and advance.
If you already have enough experience or are brushing up on techniques prior to a checkride and need a break from an instructor, sure if you want to blow time and money. 10 hours in, you don't have that, 15 hours in you don't have that. A safety pilot is a pair of eyes, that's it. So you're basically training yourself.
The only possible benefit from someone in the right seat who ISN'T a CFII would be someone who is a safety pilot with a current instrument ticket who might be willing to impart some advice if asked. But even that isn't instruction, it's more of a "tips and tricks" session.
Familiar with the law of primacy? It takes double the amount of time to retrain someone out of a bad habit then it does to train them to do it right the first time because they have to teach the person to unlearn the bad behavior and then teach them all over again how to do it right. Going up with someone who's just there to look out the window does you no good if you are trying to LEARN. It's a waste of both time and money. By the time you get back in the plane with a CFII as
@jesse mentioned, you'll waste time fixing all the things you trained yourself to do wrong because no one was there to correct you when you were doing it.
The only situation (and I wouldn't recommend it) that would even be worth it would be doing all your required training (with a CFII), learning the system COLD, getting your written done, all of that and THEN going up maybe one time with a safety pilot for fun. Even then, it's still (in my opinion) a waste of time and money. I'd rather spend the time and the money on a mock checkride from a qualified instructor right at the end as opposed to going up on my own and signing myself off with a safety pilot.
The OP wants a safety pilot to help out, but that's not what a safety pilot is there to do. The best "someone to help out" would be a CFII this early on in the training.