There absolutely is truth to it. There's even evidence when looking at the NFL expansion. Phase 1: relocate Dumbo & Storybook. Phase 2: Mermaid & BOG. Phase 3: SDMT. Rinse, wash & repeat. Each "phase" is budgeted in smaller chunks to spread out the CAPEX required. Don't think the shareholders would be very happy to see those massive capital expenditures hitting the balance sheet all in one fiscal year...
Again, the dollars are going to "hit the balance sheet" over a period of 20 years or more, depending upon the useful life Disney forecasts when the assets are placed in service.
Staggering the opening of those areas of Fantasyland had as much to do with planning and construction coordination as anything else. Development on the Mine Train was well behind other plans. Original renderings and models had that space occupied by a Tinker Bell forest / meet-n-greet.