I think you are talking about 5200. It is meant as a permanent bond and really does take about a week to set, even longer if it is used outdoors below 50 degrees. There is also a version called Fast cure 5200 and some less strong stuff called 4200. Widely used in marine applications (on boats).
5200 is a polyurethane adhesive. It does take time to cure, but requires moisture to cure, so deep in a well sealed joint (where there is no moisture to absorb), it may NEVER cure. I don't think it is designed for a joint over 1/2" deep.