they don't function on how tight they are
if you use them with the approved grease , they feel all quite loose. The tightness is a mechanical phenomena, the electrical conductivity is not always related. If you want a tight terminal, use a screw with retaining compound.
THat being said, is the crimp thickness of the spade and socket correct? 0.032 and 0.02 are commonly available, I don't think they like mixing and matching well.
I believe the 'tightness' people expect with disconnecting ancient ones in old equipment would be considered 'seized' by the manufacturer, likely to do damage to the solder joint, insulation or crimp junction during removal, so they are not designed for this. Also, brass will have a lower insertion force then other coatings/types.