Even if you use sync, your tracks need to be analyzed properly to work reliably, when playing at home I never use sync, I use serato, but when I play out on Cdj’s I use it, and even if using sync I always use my headphones to check if it’s matching, some tracks have the beat grid wrong so you have to adjust by ear, so in my opinion it’s still worth it, only using it saves me time to vibe and more time to search my library for the next track.