The higher the zeal the better quality the Crusade/Jihad in my experience yes. With 100% zeal you should get a decent sized army consisting of good troops and Nizaris, if you spam two dozen of them, then you'll pretty much have your quota of Nizaris for the rest of the campaign.

Lord Martok frowns on jihad spamming however, and has never spammed jihads in his life, so don't let him see you spamming two dozen!