I think Tom Yost recommends epoxying the joint + lashing it as a redundancy measure. However, it is not required, and actually may be detrimental in some situations, ex. when using the aluminum stringers. Make sure you learn the good lashing technique - there is a good video tutorial on this by Kudzu boats - look it up on Youtube.
If you are using quality lash and do it well, lashing is probably stronger than any other method, and allows easy dis-assembly of the joint in case you need to redo something.