For the BLTouch the slower the better. I use a faster probe first to save time in case the bed is far from the nozzle, and then a final probe at F100 for greater accuracy.

M558 A1 F350 ; Set single probing at faster feed rate G30 ; Do a single probe to home our Z axis M558 A10 F100 ; Set tripple probing at slower feed rate G30 ; Probe again to get a more accurate position

I can't say for other probes, but I think that would generally hold true. A piezo probe may have a minimum speed to register cleanly though.