The thing about comparing Disney and Universal in this way is that they’re both successfully doing the same thing: opening one big attraction or area per year.
Disney starts earlier on several projects at once, while Universal moves more quickly on fewer projects at a time.
If Disney worked like Universal, that wouldn’t mean Tron would be open by now, it would just mean that they would’ve waited until late last year to start construction, because the goal was always to open in 2021 (now 22).