I also never went collect every piece route. I collected and assembled armies to my liking. I built the majors into companies (1 unit a squad, 3 units a platoon, 3-4 platoons for a company)of their infantry, and batteries and platoons of their main battle tanks and guns. For the majors, I have at least one of each every infantry unit and at least one most of their vehicles (mostly v. 2). US and Germany are my largest armies.
The minors have smaller companies and platoons of infantry, guns and vehicles. It depends. Croatia has 1 unit, but my Finns are well represented (still looking for 5 Finnish Infantry).
I have a few more units to complete my armies. I'm thinking of collecting a separate D-Day set.