I'm not in the industry, but from talking to people that have been, VFX is one of those things that gets squeezed the most. It typically happens after principal photography is done, and the release date has been set in stone by the management and marketing machine at the studios. When you add the wide numbers of VFX houses, the lack of labor protections, and the ability to outsource to all corners of the world, there's so much competition that it's a race to the bottom with pricing and delivery dates.