There are a lot of ways to game the judge-assignment system in district courts, but this doesn’t seem to be a good example.
Under the Southern District of Florida Internal Operating Procedures, there are five divisions in the district. If I read it correctly, cases are randomly assigned to any judge in the district (regardless of division), except that the case is supposed to be assigned to a judge that sits in the originating division or one division away. So, relevant to our example, a case that originates in the West Palm Beach Division (perhaps because the relevant acts took place in Palm Beach County) would be randomly assigned to a district judge in the Palm Beach Division, the Ft. Lauderdale Division, or the Ft. Pierce Division. (The Clerk’s Office is supposed to regulate caseload across the district).
In Trump v. United States (docket sheet here), unless I’m missing something, the case was filed in the West Palm Beach Division (because the acts took place in Palm Beach County) and the case was (randomly) assigned to Judge Cannon (who sits in the Ft. Pierce Division – one division away).
Interestingly, cases originating in the the Ft. Pierce Division or Key West Divison are treated differently, presumably because Ft. Pierce has one judge (Cannon) and Key West has no resident judges. I find the internal operating procedures a little confusing, but I think that any judge in the district can agree to be on the assignment wheel for those divisions and can then be assigned cases there – assignments to the other three divisions do not appear to be optional.
The assigned magistrate judge (Reinhart) sits in the West Palm Beach division (and, of course, was also involved in the search warrant), which is a pretty clear sign that it was filed in the division, since magistrate judges are not randomly assigned cross-division. You might also note that Judge Cannon’s orders are styled as from the West Palm Beach Division.
So, in sum, the case appears to have originated in the appropriate division (West Palm Beach) and could have be assigned to any district judge in West Palm Beach, Ft. Lauderdale, or Ft. Pierce (8 judges total, of which 5 are Trump appointees, 2 Clinton, and 1 Obama – decent odds for a favorable judge, but again, it’s the appropriate division for an action arising out of Palm Beach County).