Cockpit Premium is a cleaner and protectant in one so you can just apply the product with a towel and you're done. The protectant protects from the sun and from dust, but because it's a 2-in-1 product the protectant only lasts for 2-3 weeks. I suspect that in comparison, a dedicated protectant such as 303 Aerospace Protectant will last much longer.
Personally, I use Cockpit Premium only as often as I need it. I notice when the protectant is gone as dust starts accumulating on my dash but I do not use the Cockpit Premium again until it is time to clean my interior. I live in NJ so I do not need to worry about sun exposure harming my interior, but people in hot climates (such as Florida) may want to make it a bi-weekly routine to use Cockpit Premium.