Yes, you have to get all the D and the R sides but you also spend the first year or two training/working only the D side. That gives you so much more experience on that specific sector so when it comes time to actually work the R, you already know the sector, you just have to figure out how to talk to and work the planes now. In the TRACON, you go right in to working everything with no benefit of a D side or anything to get familiar with the sector. You just have to learn it as you go with those hours ticking away. Having gone through both, the center training is 100% better designed and manageable for an AG or no radar experience CPC-IT over a high level TRACON. There are definitely those that can succeed, don't get me wrong, but the center is just a better set up for success.