It's hard to get a significant increase to the normal briefing limits in D. Del., even if both sides agree. Sometimes a judge will grant a small increase (if there's a good reason), but for the most part, they're reluctant to grant requests that will have a large impact on their workload.
Case in point: In a multi-defendant ANDA case that went to trial last month, the parties submitted a post-trial briefing schedule asking Chief Judge Stark to allow "in excess of 500 pages of briefing and an additional almost 500 pages of proposed findings of fact[.]"
Judge Stark quickly rejected the proposal and ordered shorter limits. And although he allowed "[a]ny party that strenuously objects" to file a request for reconsideration within 24 hours, he also noted that any request should include "a proposal more reasonable than the one the Court has today rejected."
It's worth noting that the agreed-upon briefing schedule didn't include an explanation for the large number of pages. It might not have made a difference, but sometimes that can help to alleviate the sticker shock.
In any event, be warned: Even if you have complete agreement with the other side, your briefing limits might get rejected anyway.