What is a process that works?
If you have monthly deliverables, is it reasonable to create a series of physical environments where each is used for a different phase of testing; Unit, Integration, Customer, Pre-production
And that, if each one of these had a four week duration, that the code could move in cascading fashion from one to the other, e.g.; September, August, July.
Or do you have to create four unique paths each with parallel phases, e.g;
Unit Integration Customer Pre-production
Unit Integration Customer Pre-production
Unit Integration Customer Pre-production
Unit Integration Customer Pre-production