I've seen results similar to what you are describing with the inductive and capacitive sensors. Some people have good results with those types of probes. But not everybody has good results. I prefer a micro switch on a Z-Probe leg. That works very reliably.
But the other thing that is very helpful is to set your Z-Probe-Offset such that the nozzle is about .3mm or .4mm above the bed. And then just dial in the height using the Z-BabyStepping while the skirt is being printed.
And I know I'm biased on this, but I've added several ways to get into the Z-BabyStepping very quickly in the Marlin UBL code base. The first way is you can over ride the 'Kill' switch on your LCD Panel to do Z-BabyStepping. If that is not acceptable, you can just double click the encoder wheel while in the Status Screen and it will go to Z-BabyStepping.
The reason this is valuable is because if you need to adjust the nozzle, it can be done very quickly and easily. And at that point, having your endstops adjusted exactly correct becomes much less important. In fact, it becomes almost the opposite. In order to protect the nozzle and the printer's mechanics, you deliberately adjust the nozzle a little bit higher than it should be to leave some room for error. And just dial in the correct height when you start a print.
But the other thing that is very helpful is to set your Z-Probe-Offset such that the nozzle is about .3mm or .4mm above the bed. And then just dial in the height using the Z-BabyStepping while the skirt is being printed.
And I know I'm biased on this, but I've added several ways to get into the Z-BabyStepping very quickly in the Marlin UBL code base. The first way is you can over ride the 'Kill' switch on your LCD Panel to do Z-BabyStepping. If that is not acceptable, you can just double click the encoder wheel while in the Status Screen and it will go to Z-BabyStepping.
The reason this is valuable is because if you need to adjust the nozzle, it can be done very quickly and easily. And at that point, having your endstops adjusted exactly correct becomes much less important. In fact, it becomes almost the opposite. In order to protect the nozzle and the printer's mechanics, you deliberately adjust the nozzle a little bit higher than it should be to leave some room for error. And just dial in the correct height when you start a print.