To be fair, in DT most players just start using pre-canned builds they are suggested by somebody at some point, they don’t really think much of synegry either. You can find builds with detailed explanations on how it all works together and how to play them on gameslantern, or in various YT videos. I’ve played 300+hrs already, and so far I only made myself may be 2-3 builds I think? And out of those, only one really from scratch, for my psyker which I played from day 1. For other classes I just use builds created by other people, with some tweaks I add when I learn more about how the class is played and what I like about it.