How expensive are environmental reviews? Is it a purely on paper/surveying exercise, that doesn't require any construction to happen first?

If that's the case, then I can understand environmental reviews taking a long time. Its similar to pre-production in movies/games, where the writing/high level design can take a huge amount of time, and is not accelerated by adding more people, but is also very cheap to do, so companies partition small teams out to constantly be in pre-production.

If that's not the case, then it probably is debilitating to construction work.