Having never had 3D printer before are these machines always erratic in there behaviour ?
no and yes i guess.
I own a flux delta and a reprap x350 pro and to say 3d printing is perfect on any of them is false. both of them can act nice and then suddenly something doesnt work like it should and all hell breaks loose.
but besides that 3D printers rarely (in my experience) behaves erratic and mostly it’s a simply fix software side or something else