Gluing

Capillary action means touching the join with a drop of thin glue and it flows along the gap. Thick glue will just sit there in a blob. Thin weld type glues are good for seams where you touch it and it will flow itself through the gap. They also tend to bite and cure quicker, ( which can be a pain sometimes!) Thicker glues, especially CA,  are good for gap filling too.

I use CA exclusively. I don't have the patience for any other and have been using CA for 20 years. Although I typically use medium viscosity, I will occasionally use the capillary ability of thin.