Yes, if you don't, you have ruined it.
I separate the point and flat just before slicing, and make sure to slice each across the grain. There are a couple of other ways to do it, but, that is the easiest, plus, folks can choose which cut they want.
I'm feeling bearish, and I'm packing a Wusthof Grand Brisket slicer from MABA
"perhaps...but then again...maybe not..."