You don't need it for hours. In fact, if you are doing it properly, it will be very difficult to build up to five minutes.
Stance training is not just deep, stationary stances. That is part of it, it builds useful strength in the legs.
However, you also need to understand what to do with that strength. In traditional Chinese martial arts (and others too) power for your technique originates in the feet and legs, and drives movement through the upper body. There needs to be other drills that you do to teach you how to use this strength and employ it in your technique.
People think that stance training is just getting as deep as you can and feeling the burn. It's not. There is more to it than that. The stance itself does not do much for you. Using it means transition from one stance to another. Not for the sake of the stance, but for the movement that is useful. The stance is just the beginning or end posture. It is the movement and the change in posture that matters, that is where you do the work, unleash a powerful technique.
Standing in a deep stance does not, by itself, teach you rooting. Rooting is an active action, you brace the feet deliberately into the ground, pressing with the legs. If you don't actively "root" then you are just standing on your feet like they are platforms. That is standing. It is not rooting, even if you are in a low stance.