No Neil, if one pot leans off you wont see it on an AFR gauge, in fact, the only real way is with 4 independant EGT sensors (on a 4cyl of course) or 4 independant AFR meters.

However, it will spot all teh more common failures, as one leaning off is actually very rare.

Fuel regs
Fuel lines
Fuel filters
Fuel pumps
Fuel pump wiring
Ecu voltage
mapping

All teh above will give a global lean off, which the AFR meter will spot at once.