Just learn the frame data on the moves you use the most then build from there. I dont memorize all the frame data from my character but at least know the data on the moves you use. I still have to look up data on certain moves so dont feel bad.
It took me a bit from DOA3 - DOA5 vanilla because the game overall changed. The training mode back then wasn't as super open as DOA5 vanilla. DOA5U added more options via R3 for 2 other pages. DOA2 I was completely unaware of frame data overall. For KOF, it wasn't until CvS2 to dig into frame data for 2D.