Readers looking for information on the procedure should look first at the Patent Case Management Judicial Guide put out by the Federal Judicial Center in 2009. It identifies as the "Recommended Approach" for streamlining the summary judgment process in patent cases "letter briefs followed by summary judgment motions," with another option being limiting the number of motions or number of pages of summary judgment briefing. Pages 6-9 and 6-10 of the Guide set forth the pros and cons of the different approaches.
Another data point is provided by the language in Judge Gilstrap's orders in pending cases this week in which he provides a brief explanation for the deletion, writing that "[a]fter carefully considering any gains in efficiency over the added steps needed to carry out [letter briefing], the Court has now determined that the Federal Rules of Civil Procedure and the Local Rules of this Court adequately streamline this process, and the Court elects to discontinue its prior letter briefing policy for summary judgment motions."
Note that the EDTX local rules have included page limits for I think 12-14 years or so, and I would also note that some courts in the Eastern District have also used limits on numbers of motions as well. My experience with that "one motion absent leave" rule in patent cases is limited - but in my experience under that rule every SJ motion we filed ended up being granted. For whatever that is worth.
Obviously different courts find different practices to work better for them, and as I posted last week, it's not uncommon for those practices to change over time. Since my practice has apparently seen the last of letter briefing for now I'll leave the opining on the relative pros and cons of the practice to others.
I hope readers find this useful.