This length of rest is quite surprising when compared with the more modest forty- or twenty-year rest periods indicated elsewhere in the book (e.g., Judges 3:11; Judges 5:31; Judges 8:28; Judges 15:20; Judges 16:31). But since the note about Shamgar that follows does not indicate a separate period of rest, it might be the case that these eighty years serve for both Ehud and Shamgar. The latter may simply have suppressed the threat of peace by his killing of six hundred Philistines. The above possibility is strengthened by the fact that the following narrative begins by referring back to Ehud rather than Shamgar as the one whose death marked the end of the period of rest (Judges 4:1).1
30 So Moab was subdued that day under the hand of Israel. And the land had rest for eighty years.