We lawyers move things around all the time. Some due date or another falls on a vacation, an expert gets sick, a bunch of files won't load -- a thousand different minor catastrophes can occur. In Delaware, the result is almost invariably a stipulation to move the relevant dates.
Typically for little interim deadlines, the Court will grant the stipulation as a matter of course. Deadlines a little closer to trial are a bit trickier. Judge Connolly, for instance, notes in his form scheduling order that "Should the parties later stipulate or otherwise request to have the [SJ and Daubert] reply brief deadline extended, the parties …