It’s pretty simple really, I start in LR because that’s my catalogue and management system of choice. I use it to cull, label, tag etc...
second, LR is very easy to make raw file adjustments right into the catalog, create versions, experiment etc... it’s just simple and fluid, some pictures don’t require much and LR makes that a breeze.
anything heavier in terms of editing goes to PS.
if you use ACR in PS, as soon as you hit done, you are not editing the raw anymore. If you want to make more changes to the raw file you need to process a new one. LR is far more convenient for those early steps until you are set.
If you are not going to use masks and layers, you are much better off in LR which in this case is non destructive vs PS.