In the end companies like Athena want to provide a solution that works perfectly for everyone. Sadly given the variety in growing methods, strain genetics, environmental conditions, etc, this is not possible. Any fertilizer provided massively will always be close to optimum for some and very far from it for others (a reason why there are a million fertilizer products for cannabis and not just one).
I believe those with experience doing formulations for different clients, such as @emdub27 and others, can probably attest to this fact. In my personal experience, optimizing formulations for specific clients based on quantitative information has never yielded the exact same formulations. Often the differences have been quite substantial.
The modifications in feeding schedules probably reflect what is working best for their highest paying clients or their own internal research. The issue with going with a company like this is that you’re always “along for the ride” and if the past formulation was great for you and they change it because it worked better for another group of people then you’re going to be in a worse situation. If they suddenly decide they want to charge 3x the cost and you already have your entire operation committed to them, it’s also going to be very hard for you to change products.
For large and profitable grows, the use of in-house made formulations - or at least contracted to be made by another party with an outright known formulation - that won’t be changed is important for future survival, reproducibility and continuous self improvement.