The single most useful thing to know about the trials is how uneven they were. A traveller could cross from a territory that had executed hundreds into one that had executed almost nobody, among people of the same language, the same faith and the same beliefs about witches. What differed was not belief. It was jurisdiction and procedure.
Three things predict severity. The first is judicial torture. Under the Roman-canon procedure used across much of continental Europe a capital conviction effectively required a confession, and torture was how confessions were obtained; each confession then had to yield accomplices, and each accomplice was arrested. England did not use torture in ordinary criminal procedure, and its totals are a small fraction of Scotland's. The second is review. Where a higher court examined verdicts, local panics were checked; where a small court could try and burn without review, they were not. The Spanish Inquisition, of all institutions, largely stopped witch executions after 1614 precisely by centralising review. The third is political weakness: fragmented territories with many small courts and no strong central authority produced the worst episodes.
The chronology matters too. The heaviest prosecution falls in the sixteenth and seventeenth centuries, alongside the Reformation and the beginnings of modern science, not in the Middle Ages, whose canon law had held for five hundred years that the night flight was a dream.