Researching a giant pile of French-Canadian ancestors -- a combination of several consecutive generations of large families and easily accessible data from Québec from the 1600s forward; and smaller piles of Irish and Scots ancestors.

Most of my French dead-ends are in the 17th century in France just prior to emigration; the notable exception being (of course) one lineage traceable through Charlemagne.

My Irish dead-ends are mainly post-emigration in the late 1800s; I have very little info from Ireland.

The trail in Scotland ends a bit further back, with some records from 1800/1802.