If you know how to use Photoshop and ACR, Lightroom is pretty pointless. The one thing it does do - and some people say does well though I do not agree - is photo management. Actually, it's slow and clumsy in that role, but you can use it if you want to. Best not to waste your time. Learn the software that works for you and don't let yourself be distracted by software that has no purpose.

Disclaimer: after using Photoshop for more than a decade, a couple of years ago I switched to DxO Photo Lab, a much better designed and far more usable package. Never looked back.