Which practice do you use and why?

Why not combine both methods? The east tract POB would be the NE corner of the parent tract, "from which a found XXXXXX for the NW corner of said XXXXXX tract bears  N 89d 45' 15" W a distance of XXX.XX feet".

I try really hard to avoid using the "Point of Commencement... True Point of Beginning" form of description. I might say "Beginning at a point which bears [Bearing], [Distance] from [POB of another tract]. Also calls for bounds.

But it's all academic here in Oregon. Any new parcels are going to be created through a land use application process which includes preparation of a subdivision plat, complete with monumented corners, described by reference to Parcels and Plat map numbers - not metes and bounds.  

In my colonial state, I love to see all three start at the same point.  Everything fits together nicely and forevermore it is apparent that they were near simultaneous conveyances.

I'd push for the descriptions to simply reference Tract-A, B or C per PB-XX Page-XXX. If a detailed description was required, my POC would be the nearest CORS station ARP or a nearby NGS benchmark and I would list my recorded coordinates of the CORS or BM and provide metadata that includes basis of bearing, date of fieldwork, grid or ground distance, and combined factors. After my preamble paragraph listing all the abutters and useful deed or plat references, I'd describe from the POC to a POB at the NE corner of the West Tract with a tie to the NW corner of the East Tract. Each would have SPCS coordinate pairs. In NC, it's common to have tie language such as, “Said found pipe being located N 45° E, 100.00 feet from a found 1‑inch iron pipe.”