I remember buying a Scotchlock kit from my "friendly" motor factor rep after he demonstrated how "easy" they were, way back in the 70's. We were in late January, on one of the cold snaps near to the M62, with an HGV fleet, so the new fangled connectors were fantastic! I would say for a maximum of a week, when the salt got into them and they all dropped off! The rep had a "frosty" reception when he returned and gave me a free box of conventional joints for free! I have used Scotchlocks occasionally since, but prefer soldered and crimped connections where possible. Salted rainwater is evil for electrics!
(especially commercial rear lamps!)