Preventive rod-bearing replacement is NOT required on the E36 M3 the way it is on the later aluminium S54 and S65 — the worry around it is largely misplaced.
The US S52 is an iron-block relative of the ordinary M52, sharing a bottom end that simply isn't known for spinning bearings. The preventive culture came from the E46 M3's S54, driven by its aluminium block, tight clearances and sustained high rpm.
Owners who do S52 bearings treat it as insurance on a high-mileage or unknown-history engine, not a fixed interval.
If you do go in, fit new rod bolts and torque them in stages — roughly 5 Nm, then 20 Nm, then a further 70 degrees.