To a degree - but VFX companies are pretty much forced to underbid themselves in order to get contracts in the first place. Several companies (Cinesite is a pr

To a degree - but VFX companies are pretty much forced to underbid themselves in order to get contracts in the first place. Several companies (Cinesite is a prime example - they underbid on John Carter heavily) underbid in the hope they'll be picked for future films as well. And because VFX is generally the last (ignoring final grading) part of doing a film (occasionally the VFX for shots is still being done up to 2 weeks before the film's released), there's a hard deadline set that the VFX companies most of the time have to meet. Often, while doing the VFX, the director's changed their mind several times regarding what they actually want, and any planning / previz that was done to agree on the shot is wasted, as is a lot of the work that was done do get to that point. You can often reuse assets and stuff, but that's about it if there's a change of plans. Thankfully over the past few years, previz of VFX is getting more and more realistic (in terms of animation / layout - the look is still quite crap), giving directors a more accurate view of what they'll be getting at the end.