When I flew for Ryanair, the Ops Manual approved criteria for conducting a monitored approach were based on visibility or cloud base. I seem to recall 300ft/1000m for a CAT 1 ILS OR +100/3000m for an NPA though those are from a rather shaky memory.
I like monitored approaches but if but if you do them all the time you are robbed of the delight of taking everything out going downwind and flying all the way to the gate...