It only covers people on the ADP payroll processing ledgers. It’s a limited statistic in that it will miss work disruptions like strikes, where people are still on the payroll but not working. For example it won’t detect the Verizon strike, and I don’t know if they correct for that in the revision or not.
It also only covers private employment, not govt so it will miss any hiring/firing there. Govts are laying off as of late so the BLS employment numbers Friday might be worse. Absent the occasional strike I do like the ADP numbers because it shows how healthy the private sector (i.e. REAL economy) is at the moment.
Which right now isn’t that healthy.