If these "tuned" values are calculated based on the maximum capacity of your server and you put the same values to every site, you'll consume your resources multiple times. Instead, these values should be distributed between the pools so that the sum from all pools is equivalent with the "tuned" value. And this is if the calculations from Sebastian Buckpesch are reasonable.
Not every site needs the same amount of resources. You should know which of your sites gets more visitors or have more heavy scripts etc. etc. and allocate the resources accordingly. If you run out of resources, you need to allocate less, replace the hardware or whatever is needed to solve the issue. If a single site runs slow and you can move some resources from another site, do that. It's not as simple as in the article and there's no comprehensive Excel sheet that can tell you the truth.
Whatever you do, keep your sites in separate pools with separate user accounts. Otherwise a compromise on a single site can spread across all your sites.