That's bad faith accounting of Disney construction. Yes, some things took way too long, but in the case of Pandora, the arguments get very disingenuous.
And that's because Pandora's construction gets talked about almost exclusively in relation to Universal construction.
From the time 'shovels hit the dirt,' a Potter land was built in 2 1/2 years. Pandora built in 3 1/2 years. But so often, that half year gets rounded down in Uni's case and rounding up in Disney's case so that it can be said, falsely, that it took 2 years to build a Potter land and 4 years for Pandora. The construction time between the two is one year, not two.
Similarly, because Uni doesn't announce their projects way in advance like Disney does. Some count the announcement time as part of the construction time. Which, again, is disingenuous. You need to compare apples to apples, and the apples to apples comparison is 'shovel in the ground' (which includes site prep, such as razing previous structures).