I'm going to be a bit contrarian here, at least as far as this thread seems to have gone.
I think that
@Isa.nerwen could learn quite a bit as a DM/DM candidate.
DMs will practice everything rescue divers learn. Usually, whenever they're in the water, you will have an opportunity to use something you learned in rescue.
Repetition == mastery.
Depending on the agency, she'll be required to demonstrate every open water skill with demonstration quality, while neutrally buoyant. That doesn't make you a snake eater, but it far exceeds the standards of most open water courses.
I spent all my free time in the water (monitoring students, waiting to help etc.) working on skills, and there's something to be said for having access to basically unlimited dive time. Maybe it isn't all your time, but it's still time underwater.
The question is, where do you get the most value for your dollar - in tech training or dm training? That's a hard question to answer. Most of the tech divers I know and work with are instructors, so they've had the experience of dealing with a panicking open water student who's trying to kill themself underwater. The DM side of that training is the "I can get you and me to the surface, alive" and the tech side of the training is more about learning breathing, buoyancy, trim, and positioning. Both are valuable and in my experience, the best divers have learned both sides.
Ok, all that said, my recommendation would be for a new diver to take tech training at least at a fundies/intro to tech level, and then proceed with the path of least resistance into getting further certs. There are few people who don't have something to teach you, and when you work with students, they're going to teach you a lot of things, but they may not be what you want to learn.