I performed Intersect Analysis on one polygon shapefile and one polyline shapefile. I didn't specify any tolerances, and both SHPs were projected into the same UTM before performing the analysis.
Expected behavior: one line criss-crossing a polygon will always be split into multiple lines
Actual behavior: lines are only sometimes split
Evidence: # lines input file = 2663; # lines output file = 2958; so, some splitting is happening. Image below is only one FID highlighted, but clearly is 3 segments and should be 3 separate FIDs