Are you talking about gluing long grain to long grain joints like in gluing a tabletop together? If thatís the case, Iíve never used a router for that and here is why - the fit would depend on the fence, and getting a matching joint would be nightmare. If thatís not exactly the case, what joint are you referring to?
As mentioned, long grain to long grain joints donít need dowels, splines or biscuits for strength. These are used (often in industrial applications) to help align the edges to decrease sanding or planing later, not to add strength, though that is sometimes taught in industrial arts classes. Another factor to consider is that dowels and biscuits will have the grain going in a right or oblique angle compared to the boards they are holding together, and will change dimensions differently than the wood. Bumps in the joint above the dowels can appear years later. If you are joining long boards using a ship-lap joint, unless you are doing it for the appearance (with a space between them for example), or to account for wood movement, you donít need to do all that work. Just glue the boards together without anything.
Finally, are you using half lap joints to glue vertical and horizontal pieces together? If so, the half lap may not be the best choice. When a half lap joint is subjected to any twisting motion (I think a cradle counts), they can pull apart more easily than a mortise and tenon.