Been keeping track of Eveline’s crystal drop rate since version 0.35 and it would appear she drops 1 crystal every 20-30 uses, at least at level 50. Not sure if level effects it since most people are very high leveled Eveline.
Assuming they fix the game so that followers that are level 50 max stop dropping their crystal, a player that uses 100% of their ore to run Eveline and yield 1 crystal every 2 days will have all followers completed after 1,050 days, which is around 3 years. To put this into perspective, the previous system with glyphs would have taken only 2 years to do the game. This also assumes they add the ability to NOT get repeat crystals of maxed followers, which currently is NOT a feature. This means the current system is WORSE than before for maxing all followers.
This is due to 525 crystals currently being missing from side quests in order to max all followers. While chests will also drop some on occasion, the current follower economy in its current state with repeat crystal drops could take upwards of 3 years, an increase of over a year compared to the previous system.
This also poses a new issue to the game, in that 100% of ore has to be used on Eveline for around 3 years in the current state of the game, making ore nothing more than a “keep Eveline crafting” resource.